


It’s In The Blood

by TheBeingOfEverything, TheHopelessWeeb



Series: It’s In The Blood [1]
Category: Ao no Exorcist | Blue Exorcist
Genre: ;-;;, Alternate Universe - Canon Divergence, Angst, Author Is Sleep Deprived, Biting, Blood and Gore, But what’s new, Demon Sex, Hurt/Comfort, M/M, Nightmares, Rin is not having a good time, Rough Sex, Tail Fucking, The Author Regrets Nothing, Whump, demon!Rin, i did it for the angst, i hurts my bby boi, im sorry, its not gonna get better, later tho, most likey, not sorry, poor lil Kuro just watching out for him, probably, yukio’s an ass that hates his brother
Language: English
Status: Completed
Published: 2019-09-20
Updated: 2020-03-23
Packaged: 2020-10-24 13:10:05
Rating: Mature
Warnings: Graphic Depictions Of Violence, Underage
Chapters: 5
Words: 23,792
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20706536
Author URL: https://archiveofourown.org/users/TheBeingOfEverything/pseuds/TheBeingOfEverything, https://archiveofourown.org/users/TheHopelessWeeb/pseuds/TheHopelessWeeb
Summary: Something’s wrong with Rin Okumura. The horrific night he awakened his demonic blood has come with a slew of nightmares that eat at his mind and sanity even in the waking hours. But with the lack of sleep piling up, friends begin to look like enemies and even his own brother might hate him, at least, that’s what the nightmares tell Rin





	1. When the Abyss Calls

**Author's Note:**

> Hey guys ! It me >< I know I’ve been gone a while but I’ve been in a major slump with my other two fics so I wanted to try writing this fic for another fandom that I absolutely *adore* to try to help me get over my funk lol I hope y’all like it! And kudos to my fren TheBeingOfEverything for helping me tag and being an awesome beta \o/ they’re total awesomeness and you should check them out!

Rin Okumura has had a lot of nightmares since his demon blood awakened within him. Visions of his dad’s death, of his dad still trying to save him even though he was possessed and bleeding out on the floor of the monastery, of his own brother saying that he should die and that he was to blame for everything plagued his mind every night for the past year. As if he didn’t blame himself enough, as if he didn’t _hate_ himself enough for causing Father Fujimoto’s death, he was met with pure hatred in his brothers eyes at every waking moment and as much as it hurt him, he just couldn’t bring himself to hate Yukio because he knew that his little brother was hurting as much as he.

§§

It was about a week after their birthday when Rin’s nightmares went from bad to worse. 

Before, the vague dreams he had all passed in a red blur that left him more tired than the hours he’d managed would suggest he’d feel the next day. If he was more irritable than usual in class, a little quicker to feel fangs extend in his mouth at minor infractions, he forgot it when he made up the missed sleep.

Not recently. Now, he remembered his nightmares.

Images of his classmates, of Yukio and Shura, beaten and bloodied and dead on the ground around him as he stood in the midst of a raging **_blue_** inferno. 

At first, Satan would be there- always gloating about killing everyone just so he would finally _break_. 

He never got any rest after those, maybe getting an hour or so before he would wake up in a cold sweat and seeing blood on every surface. 

Yukio lay across the room on his bed blissfully unaware as Rin sat up on his, gasping for breath and clutching his chest. _It hurts! Gods why does it hurt so damn bad? Why now?_

With a resigned sigh, he got up to take a cold shower, hoping it would calm his frayed nerves and left the room.

\---

A sharp crack echoed in the room following Rin’s exit.

Kuro snapped his head up to look at Kurikara where it lay by the desk before widening his eyes and looking towards the door where Rin left with alarm. _Oh Rin...what’s happening to you?_

§§

Today was just _not_ his day. 

Rin kept dozing off in class more than usual and being constantly woken up by his teachers wasn’t helping either. 

Of course, word reached Yukio too about his behavior and he got a lecture over the phone about it until he saw him again in the halls and got more of the same. It seemed like every little thing he did just pissed Yukio off as he couldn’t so much as look in his brothers direction without getting a glare in return. 

He silently prayed to any deity that would listen that cram class tonight wasn’t with his brother or was a simple enough lesson that he could get away with a much needed nap. It seemed though, like every day, luck was not on his side as his brother was teaching class and already trying, unsuccessfully, to hide a suspicious glare as soon as he walked through the door. 

Sleep would not be in the cards this class, Yukio was on high alert. 

Sighing, Rin walked over to his desk and dropped down in his chair while Shiemi looked on in slight worry when she must have noticed the dark circles around his eyes.

Which only annoyed him even more. The only other person he’d seen with bags as bad as his under his eyes was that clown, Mephisto and he didn’t know why when he had demonic healing that should get rid of things like that!

Clearing her throat, Shiemi quietly spoke to him in the free time before class started, “R-Rin? Are you...are you ok?”

He groggily opened one blue eye, the action only bringing to his attention how much his eyes burned with exhaustion- and looked at her from where he was slumped against the table. “‘M fine. Don’t worry about it.”

Before she could say anything else, his eyes slid shut, feeling snoring as he drifted off, unable to keep his heavy lids up anymore.

\---

Shiemi whipped her head around when Yukio sighed from the front of the class and pinched the bridge of his nose. She stared as he began walking towards the table before locking onto his sleeping brothers form with a log exhale.

“Nii-san…”

Rin didn’t even twitch.

“_Nii-san…!_”

Nothing.

“_Nii-san!!!!_”

Yukio grumbled when he _still_ didn’t move an inch and he looked towards Shiemi when he caught her shaking her head. With a last grumble and a resigned sigh, he walked up to his desk and began teaching class while Rin slept.

Shiemi glanced over at Rin, wondering if she was seeing things or if his body trembled in his sleep.

§§

He found himself walking in..._something_ and, when he noticed the bodies everywhere, he realized what it was as bile rushed up his throat and he leaned over to relieve his stomach of what little it contained.

_Blood_ and the still fresh corpses of his brother, Shura, and the exwires all seemed to look up at him pleadingly before they were burned to ash by an all consuming blue flame. 

_Not again, please not again._

_I can’t- I can’t!_

His eyes widened in horror when he looked up to see Satan cackling madly while pulling the fingers from a still alive Shiro as he screamed- just like that night but on horrible repeat like an old film, skipping on the reel to play back the scene forever-

-And he _ran_. He ran and screamed and cried and **_begged_** for Satan to stop, just stop! Bring back his dad, his friends, his brother.

With terror lashing his mind, one question burned on his tongue as he looked at the elder demon with tears and _rage_ in his eyes.

“_Why?_ Why did you kill them? Give them back you bastard!” He roared into the bruised sky above him, dark reds and purples making a swirling nightmare realm of his surroundings.

“**Me? Kill them?? Don’t make me** **_laugh_** **boy. I didn’t kill them- your so-called** **_friends._** **Why don’t you look and see exactly** **_who_** **killed them?**” He cackled that mad laugh Rin remembered each night and grinned widely, showing off his fangs as he looked back towards the direction of familiar voices and blood curdling screams.

His eyes widened in horror as he took in the scene before him. _He_ was standing over his friend’s lifeless bodies as his razor sharp claws dripped with their blood and _he_ was grinning in some sick twisted form of glee as their bloodied corpses looked on in _fear_ and _betrayal_ at what _he’d_ done.

All reflected back in the pool he stood in. He could see the warped flames of his pupils, how inhuman he looked. Like a demon. Like a monster.

“**You see boy. It isn’t me who you and your** **_friends_** **should be worried about. They should be worried about the** **_demon_** **hidden amongst them like a wolf in sheep’s clothing. They should be worried about** **_you._**” His endless cackling mixed with Rin’s screams as he woke up in a cold sweat and in a dark classroom.

His breathing came out harshly and he tightly gripped his chest through his shirt in a vain attempt to calm his rapidly beating heart. It ached, it _hurt_, he just wanted it to _stop._

Blue flames licked his form, which he paid no mind to as all he saw, even in the dark, were the lifeless and bloodied corpses of his friends, Yukio, and Shura. They’d followed him into the waking world, layering over the surface of the room until he could almost smell the overpowering scent. Their blood covered the floor and their entrails hung from the door like they were macabre decoration. 

He could _feel_ the blood dripping from his hands and the sickly sweet smell permeated the room which made his mouth water and fangs ache. 

Rin quickly shook his head in hopes to get rid of the scene before him and tears filled his eyes as he gripped fistfuls of his hair. _What is happening to me?! Please! I...I can’t do this._

His head snapped towards the door when he heard a cough and he saw Yukio leaning against the wall with his arms crossed and the usual glare on his face that Rin had no trouble seeing. 

Yukio must know, he must know the danger Rin presented, what lurked under his skin. That’s why he looked at him like that! Why nothing Rin did _ever_ seemed good enough. 

Fine, he would deal with it, it wasn’t like he hadn’t his whole childhood from every other teacher he’d had. Rin grabbed his bag and Kurikara and headed towards the door only to stop when he stood up and blocked the way. 

The confrontation couldn’t be avoided then. Rin hid a sigh that weighed heavy in his lungs while facing the judgment in Yukio’s eyes, ruffling his sleep-mussed hair like he’d done many times before in the face of his twin’s ire.

“Mind telling me what that was about in class today?” Yukio would’ve sounded sincere and he would’ve mistaken that for worry if not for the glare that now seemed permanently etched on his face.

Rin was right in front of him now and this time the sigh dragged past his lips, the sleep he’d just managed only serving to make him more tired, somehow. He had to clench his teeth from the upcoming headache that had joined him upon waking- and he did _not_ need this right now.

“Not now Yukio. Maybe later ok?” He tried to push forward only to stop when he felt a grip tightening on his shoulder.

“No Rin. I want to know what the hell that was about,” Yukio snapped, patience lost and gaze narrowed, “I’ve gotten several other teachers coming to me about you today- never mind this whole past week.”

His headache was growing worse, the throbbing in his head almost unbearable, and his grip tightened around the strap of his bag. But his vision seemed clearer, the pulse in Yukio’s neck catching his attention and he fixated on it, on the suddenly loud beat of his heart in his chest.

“Yukio. **Not now.**” He couldn’t hear his own voice through the rushing of blood through his ears and he reached up to move Yukio out of the way with a light push past him that still sent him aside. He couldn’t think, hardly noticing the way Yukio winced in pain from the impact and slid down against the doorframe as he continued walking out of the building.

He just...needed some time alone and fresh air and then he’ll feel better, right?

Right….?

Something splintered, the sound reaching his ears but getting swept under the viscous mire of his thoughts.

_Crack_

**Notes for the Chapter:**

> so um I started a discord server >< come scream at me n stuff https://discord.gg/NqTPyF8


	2. Broken Mirrors

**Summary for the Chapter:**

> Rin is getting worse. The exwires noticed but what can they do? Or is it too late??

**Notes for the Chapter:**

> AAAAAA thank you all for liking this and MAJOR thanks to the lovely, most awe#awesomeness TheBeingOfEverything for being the bestest beta and for ur wonderful ideas ><

Fresh air hadn’t helped.

Another sleepless night passed in a kaleidoscope horror. 

The nightmares only seemed to get worse, more bloody and more vivid, after that run-in with Yukio. Something had changed between them too and now Yukio wouldn't even look at Rin anymore. At the level of exhaustion he was at, Rin was just too tired to care. 

One nightmare seemed to stand out more than the others. Satan wasn’t in sight but Father Fujimoto’s screams could still be heard as Rin once again stood in an endless pool of blood. 

Rin could only look on in silent terror as _he_ stood amongst the bodies of everyone he’d come to know and care about. The urge to beg for some kind of mercy- to plead alone in the red pit of his personal hell that this nightmare wouldn’t get any worse.

Like always, no one answered, no came for him, and he _screamed_ when Yukio stood up and glared at _him_ with bright blue eyes that Rin couldn’t even focus on past the hole punched straight through his chest that drew his gaze.

His ghosts spoke to him, always condemnation, always cursing his nature- spite on their lips.

“I always knew you would betray us. You _demon! Monster!_ You should’ve never been born!!” Yukio’s voice- always the worst, the loudest- held all the hatred built from years of resentment and was only met with a mad cackle from _him._

“**I knew you never liked me Yukio but I always tried to make things better cuz you’re my little brother. But now….**” _He_ put the hole in Yukio, felt the hard bone and hot wetness his claws dug into without mercy- with the same care he paid when preparing a meal, searching for the delicacy that was organ meat. 

His tapered tongue hungrily licked up the blood from his claws and he took a bite out of the long organ he pulled from inside before flashing a fang filled grin at his younger brother. “**Now, I honestly don’t care anymore and without you in the way, I’m** **_free_** **to do whatever I please.**”

Rin heard an inhuman scream and realized it was him as he watched Yukio’s lifeless body finally crumple to the ground like the strings had been cut while more blood than a human body could hold seemed to pool around him. The mad laughter resounded in his ears as the _monster_ in front of him turned his blazing blue eyes in his direction.

“**You can’t run forever little** **_human._** **This is what** **_we_** **are. Who we were** **_always_** **meant to be.**” Despite the horror, despite the sickness curdling in his stomach and burning acid in the back of his throat, the words called to him in a siren song. Just like the overwhelming scent filling his nose and the ozone-tang of power on his tongue.

“**Accept the power, Rin. Accept** **_me_** **and be free from these pathetic little worms trying to keep you caged like a beast.**” _His_ words swirled in his head and a part of him deep, deep down wanted to _listen_. Wanted to be _free_ and let the world **_burn_** in brilliant blue flame.

Rin grabbed fistfuls of his hair and started screaming at the demon in front of him, tears filled his eyes but they quickly turned to steam as a roaring inferno of blue surrounded them both. 

-And then he would wake, tears dried on puffy eyes, body aching like he’d been in a fight, and yet again, no sleep to be found.

After so many red soaked nights, Rin almost wondered if he would begin to view the dreams as normal- if this state he’d reached would become his new reality.

The thought of growing desensitized to the monstrous impulses he acted out in his dreams nauseated him, made him dry heave in the early morning hours as his body and mind rebelled at the notion.

But in the back of his mind, the dreams lingered, the words lingered, the urges lingered.

Nobody seemed to notice.

Rin curled forward onto his desk.

Nobody seemed to care.

He was alone.

§§

A slew of nightmares waited for him every time he closed his eyes, now.

The attempts by his teachers to get him to focus in class dwindled until even the most ambitious let him be. Mutters about his getting special privileges to be allowed to go to the prestigious True Cross Academy reached his ears as if through water and he had to laugh because they were right! He never should have been in their school, mucking up their elite lessons for intelligent, hard-working students anyway. 

This wasn’t the place for him. It never had been. Even Yukio had known it. Bon had called him out for it too, asking why a slacker like him was even trying to become an exorcist.

At this point he was too tired to do anything but shuffle to classes, sit in a haze, and make his way to the derelict dorm to sleep.

But that didn’t stop the talking. Didn’t stop the _people_.

The bell rang for the day. Rin slumped into his seat and tried to ignore his pounding head.

Aside from a derisive snort and a hard glare, his teachers just went on teaching like he wasn’t even there and honestly, he’d rather be anywhere _but_ in their classes. 

Because it was in those classes that another, worse, distraction took his attention.

Even as Rin napped unsuccessfully, he could still somehow pinpoint each and every heartbeat of every one of his classmates and teachers. 

It lingered there on the edge of his awareness. The blood pumping through their veins made it impossible to focus on anything else until his fangs lengthened and _ached_ behind closed lips. 

Clawed fingers wrapped around the legs of the desk when everything just became so _unbearable_ and, before Rin even realized it, one of his fangs pierced his bottom lip harshly and his blood pooled in his mouth. 

Paing sliced through him, but it was secondary to the way his body locked up, frozen at his desk.

Swallowing the warm liquid was like lighting a fire within him and he wanted more, _more_, **_More!_**

Oh god. Rin’s eyes snapped open, breath huffing through his nose in a harsh pant and all he could smell was the heady liquid now staining his lips.

He jolted into awareness- more awake than he’d been all week- and covered his mouth before stumbling from the classroom with a hurried collection of his things, pointedly ignoring the token complaint from the teacher. 

Hallways passed in a blur, led more by memory than his senses, all utterly consumed by the injury he couldn’t seem to stop gnawing at- couldn’t seem to let heal.

In the blissful silence of the bathroom, he locked the door and immediately went to the mirror while gripping the edges of the sink so hard that the ceramic cracked.

Not even the damage he’d done could stop him from looking where his gaze had drawn to.  
Panic had him trembling where he stood, gaze flicking across his features as if it would change and he’d be normal again. 

But no matter how hard he stared, the truth never changed. Rin shivered. His heart clenched with a choked sob.

Elongated fangs filled his mouth and slit red pupils danced in a sea of blue flames within his eyes. His ears were longer and, when he looked close enough, he noticed small strands of icy blue that began at the roots in his hair.

This time the sob broke free.

_Wh-what the Hell is happening to me?_

His reflection warped in the mirror with his tears until he saw images of bloodied and gutted bodies- his nightmares following him into the waking world- and he could only look on in stricken horror as _he_ appeared in his stead.

And he spoke.

“**Things will only get easier for you if you just accept me, accept the power flowing through your veins. You can’t spend the rest of your eternal life running away from what you don’t like, Rin. From reality.**” 

His voice was otherworldly. Demonic. And even though Rin _hated_ him, would rather listen to all the boring teachers in the world if it meant not having to listen to the monstrous things he spewed... 

...He was just too damn tired to argue.

_I can’t keep doing this. I don’t know how much more I can take_. Rin pled with the creature in the mirror. It did nothing.

A silent cackle from bared fangs- fangs that they now shared- was his only answer.

If Rin just, just…_let go_ and _gave in_ to his other self- to the saccharine crooning from those warped lips and gleeful expression, then maybe he could finally _sleep_.

God he just wanted to sleep.

Rin started to say something in agreement but stopped short when he heard a chitter of mad cackling from his other.

Anger flared in his gut and had him gritting his teeth in response and glaring daggers at the reflection.

“**Oh, come on, Rin! You’re not giving up** **_that_** **easily are ya? Maybe Yukio is right about you then…that all you do is run away from your problems with your tail tucked between your legs. When the going gets tough you get going, is that it? Bwahahahaha!**”

How _dare_ he-!

Rin’s grip on the sink grew tighter until his claws broke off pieces of the ceramic and he _snarled_.

“Shut the _fuck_ up!” Before he could control the impulse, the mirror shattered, his fist gone right through the tile on the other side. He paid no mind to the blood dripping down his mangled hand and onto the floor, still shivering with the violent rage curdling his insides.

But it worked. His double had fled with the broken glass, the laughter and mocking words no longer called to him to _give in_. Rin had escaped them for the moment.

And with that violent escape he’d also forced back the demonic attributes

Taking deep breaths for several torturous minutes, Rin managed to calm himself down and left the bathroom after checking for sure that his appearance was back to as human as it would ever get again.

§§

“What the fuck was that?” Bon breathed, fear sending his heart galloping behind his ribs at the sight of Rin Okumura throwing a fit in the men’s bathroom.

There was something very wrong with him, Bon gulped.

He forced his legs to move back to his own class and tried to convince himself that he would confront Rin about it the next time he saw him.

Wild blue flames snapped at his determination.

Bon shivered and couldn’t tell if he would be made a liar or not, while the stories of the horrors of the Blue Night bit at his heels.

§§

Rin was thankful that the cram class that night was one of physical endurance and he hoped that it would take his clouded mind off of things. Despite the lack of sleep, the earlier violence had stirred something in him that demanded action. A restless energy that wouldn’t be soothed.

He and the other exwires were back in the arena where they first had an encounter with a Leaper and were tasked with trying to outmaneuver a Naberius in teams of two.

Just- why Bon, of all people? Rin wanted to moan the complaint. Normally it was fun to play around with the dedicated exwire, egging him on with light teasing to get a reaction made for great entertainment on a boring day.

But when they’d had classes earlier together, Bon had been on complete edge around him- sending the hairs on the back of his neck to stand. Rin had fought the growls that wanted to come out the entire time when Bon wouldn’t stop staring and he couldn’t figure out why.

And his own body still hadn’t relaxed after that talk with _him_ earlier. Those words just kept repeating in his head.

Words of acceptance. Words of power. Words of chaos and giving in.

But class continued regardless. Rin began trying to burn off his edge by evading the rot demon with Bon.

Why couldn’t he stop thinking about it- about anything at all?

_Give in give in give in_

Just let me stop thinking. Just _stop_.

_Give in!_

_His_ voice just kept getting louder and louder in Rin’s ears and he couldn’t even hear Izumo yelling for him to ‘Watch out!’ before it was too late. 

Pain cut him like a knife- like fangs- like-

-The Naberius had him pinned on the ground by the throat and he suddenly felt that he couldn’t breathe as the demon’s saliva dripped on his cheek. His vision was fading and the last thing he heard was footsteps running up to him, worry evident in the fading voices. 

Rin could taste blood in his mouth. The sweet liquid brought with it a burning heat as his whole body ignited under his skin and he barely registered a clawed hand wreathed in blue flame reaching up to grab the demon by the neck. 

He grinned a fang filled grin as he stood up with the demon still in his grasp. Its desperate attempt to break free only amused him and a sharp giggle bubbled from his lips as he brought the pitiful rot demon closer so that it was mere inches from his face.

Rin’s voice didn’t sound like his as he spoke, soft, so that it seemed to invite his audience to lean in closer to hear what he said.

“**You’re gonna regret doing that, you pathetic bastard.**”

Horrified cries came from his on-lookers as they could only watch while the demon’s thrashing increased before Rin hummed with a gentle smile and ripped out the throat in his hold, setting the Naberius alight with hissing blue flames. 

Beautiful. The fire smouldering on the remains of the demon that dared attack him felt like home. A wild cackle twisted from his lungs as Rin stole the black blood he hadn’t burned on his tongue that he’d wound around his clawed fingers.

Then he turned to face the silent humans, bored now that his prey had perished in the blue flames and hoping they would provide more entertainment. He still had energy- still wanted to _play_.

But their expressions said they didn’t feel the same.

Why were they watching him like that? Like he was some kinda monster?

Rin snarled. His friends flinched back.

“**What? You gonna tell me I shouldn’t kill demons? Or was I supposed to let it rip my throat out instead? It’s not like I did anything** **_wrong._**”

Bon got over his shock first and gave him a look that seemed to say ‘_Are you serious right now_’ and, even though he was terrified, he opened his mouth to say something-

_Go one, tell me what’s got your heart beating like a rabbit’s, Bon._

-But before he could, agony drove spikes deep into his skull, a whine streaming from his lips as he clutched his head and dropped down on his knees.

Screaming bounced in ear-splitting echoes around the room until he realized they came from his mouth. 

He fell, the drop the only thing he registered as unconsciousness claimed him before he reached the ground.

§§

“Okay there’s something seriously wrong with him,” Bon tried to say with his usual bluster. But his words came out weak, questioning, and he couldn’t take his gaze from the ashen pile that used to be a naberius. 

“You think it’s the sleep issues?” Shima asked, but even he sounded unsure- scared.

“He won’t talk to me- he won’t talk to Yuki, either,” Shiemi said in a broken whisper, tears bubbling in her eyes.

Izumo scoffed from her position behind them, body still shaking, “This isn’t something we can handle- are you guys kidding me? He just freaked and lit a training demon on fire- and hey!”

She shouted at the stoic Exorcist on the phone with someone, “-what kinda class is this? Aren’t you supposed to be keeping that thing on a leash? We almost got killed!”

Their teacher hung up, gaze solemn.

“Please return to your dorms and take Mr. Okumura with you.”

They watched him leave without another word to them, a creeping fear settling in their bones at the peaceful expression on Rin’s face.

Even when he’d slept in class the past few weeks he’d never looked so relaxed.

It was almost as if killing the demon had allowed him to sleep well for once.

They didn’t know what that meant for them. What it meant for Rin.

They left him with a stoic Yukio at the dorm, watching the door shut with grave finality.

There wasn’t anything to do but go to their own dorms.

Sleep eluded them.


	3. Bonds

**Summary for the Chapter:**

> Baby boi is back to normal yayyyyy! Will it last though? Lmao probably not and while everything seems fine, our favorite lil demon boi is thinkin of ways to break free and cause chaos
> 
> And he might’ve found the best way to do it too, after all, whos Rin to deny his “little brother” heheheh

**Notes for the Chapter:**

> Hi hiii Issa me again :D happy Halloween to all you ghouls and goblins and I hope you enjoy this chapter! I know I sure did ;)

Rin slept, blissfully unaware of the demon that stood in the shadows of his dorm room watching him. 

Yukio had been helpfully sent away on a mission, leaving him to do what needed to be done, free from interference. Moonlight filtered in through the open window and a cool spring breeze caressed the white locks covering Rin’s eyes. Looking towards where Kurikara lay by his bedside, the demon moved into the light and reached towards the sheathed sword to examine the damage done. 

He tsked as he looked over the burnt and blackened wood, noticing all the scorch marks along the hilt. A complicated mess. This would cause unnecessary bumps in his planned timeline. 

Too deep in his thoughts, he failed to notice a pair of eyes warped with blue flame and narrowed into slits watching his every move as he bent down to cover the sword up and lay it by the desk.

§§

A clawed hand wrapped around his wrist, the crushing force grinding delicate bones together. He hid a wince at the pain as black claws lengthened and dug harshly into his flesh drawing beads of blood. His face was a mask, expertly concealing any emotion, as he looked to the young demon now sitting up and staring at him.

**“What do you think you’re doing, Mephisto?”** Rin asked with a tilt of his head. His tone spoke of authority unquestionable. Much like another embodiment of Gehenna did, in fact. It spoke of power absolute.

He swallowed the instinctual urge to kneel and beg for forgiveness in front of Rin, who looked so much like their Father when he was like this. 

“Now now, dear brother, I’m just admiring the beautiful craftsmanship of Kurikara. Though perhaps not so beautiful anymore, after its been tarnished.”

The grip around his wrist turned punishing and he could feel the strained bones snap as he was forced to the ground even while Rin remained sitting. The temperature of the room grew and Mephisto could feel the beads of sweat trailing down his neck. 

But he didn’t dare look directly at Rin. To look away, to meet his gaze head on, both would incite violence in Rin as he was now. The presence from Rin grew heavier, pressing down on Mephisto like Rin would snuff him out- or add him to his greater fire. 

Calculating eyes seemed to pierce right through his very being, even the indirect gaze he kept on Rin from his peripherals sending his hackles rising. Mephisto realized with a start that this was not the Rin he knew and that Rin’s presence, his power, was more like Satan than he first believed.

It wasn’t time yet, for this Rin to make his debut, never mind the problems it would cause in his fledgling pawns. He would need to seal him before things grew even more troublesome.

**“It would be wise not to lie to me,** **_Samael_****.”** That was the call of his name, his _true_ name. Rin continued in a voice that vibrated with limitless power, **“I’m not one for being patient so you might wanna hurry up before that delicious blood of yours coats these walls.”**

A dangerous growl left Rin’s throat after he’d made his threat as he licked his lengthened fangs in further warning. 

When Rin called him by his true name, a darker aura surrounded him, seeping from his core to permeate the room. Samael stood to sneer down at the foolish demon, removing the vice-like grip from his wrist with ease.

**“I see that you know my name without me even introducing myself, my dear, young prince. But for tradition’s sake, let me formally introduce myself.”** He bowed, lips parting in a sly smile that bared needle-point fangs, **“I am Samael, Demon King of Space and Time, Second in Gehenna. It’s a pleasure to make your acquaintance, Rin Okumura, Prince of Gehenna and sole inheritor of the blue flame.”**

Samael stood again, gesturing to indicate Kurikara in a wave meant to look careless, **“Now, it’s not time for you to awaken yet so would you be so kind as to go back to sleep before things escalate?”**

§§

Every word spoken by Samael seemed to put more pressure on Rin and he found himself flinching back in fear of the ancient power until his last words registered in his mind. Instincts made it difficult to get off the bed, but they pushed him to test Samael, to challenge. 

Fangs elongated and bared in silent display as the sweltering temperature in the room plummeted until their breaths made little puffs of steam in front of them. It didn’t matter. Rin stepped towards Samael, forcing him to step back or risk incineration as royal blue flame wrapped around his form. 

Now. His hand lashed out, wrap a clawed hand around Samael’s throat before he could even register what had happened. The widened eyes and hitch of breath he got for his threat had a dark purr rumbling through his chest. So, why not up the ante? Blue flame twisted with a thought, hungry as it burned down his arm towards Samael. He saw the flickers reflected in those green eyes and bared his fangs in a warping smile.

Second in Gehenna, huh? He _was_ Gehenna, and Samael would learn that by the end of this night.

§§

Blue Flame raced towards him and he saw another long passed event where that power had nearly bisected his skull.

He found himself furrowing his brows, confused when the smell of flesh burning from bone didn’t reach his nose. Opening his eyes saw him faced with the wicked smirk and warped irises of Rin’s gaze. Then, the clawed grip on his throat tightened until he thought the force would crush his windpipe and he choked. 

Calculations raced in his mind. Why had Rin forgone carrying out his threat? Staring into those vicious eyes, he didn’t think it was mercy.

Samael’s mouth gaped in silent breaths as his throat creaked under the strain. Then, without hesitation, Rin let his power loose. Despite his constricted airway, a sharp yelp of pain escaped him as he felt his skin freezing to the point that the flesh cracked and fell off in tiny pieces. 

Rin laughed, black ice on his tongue as the delight there sent unbidden shivers through his vessel.The already freezing temperature of the room dropped until a thin sheen of ice covered the walls, floors, and furniture and Samael was reminded of the subzero temperatures in the deepest parts of Gehenna where no demon could go lest they be frozen instantly. 

Where only blue flame survived at the core the the world.

His vision spotted, head beginning to burn from lack of oxygen. Rin spoke, casual, as if he had all the time in the world.

**“You know, it’s interesting what you can find out about your own powers when you’ve been locked away for so long,”** he shook Samael, an idle motion of his hand, grinning at the way he swayed from weakening limbs, **“It seems that not only have I inherited Father’s burning blue flames but my own abilities let me change the temperature of my flames.”**

_Fascinating._ Rin remained an utterly singular creature. Samael wanted to croon at the demon killing his vessel with callous indifference.

**“Now, it’s gonna raise a lot of unwanted questions if I end up killing you so, let’s make a deal, Second in Gehenna.”**

Rin let go of Samael’s neck before sitting back on his bed and, like a switch, the temperature of the room returned to normal as his blue flame disappeared with a hiss. He caught himself before he dropped to the floor, fixing the disarray Rin had left his suit in. With his other hand, Samael held his slowly healing throat while looking up at Rin with a thousand questions burning on his tongue, but forced himself to speak as to the deal he’d. 

There were few things Samael enjoyed more than a good deal. And Rin would find he had a bit of an edge when it came to making deals.

“What did you have in mind, Rin?”

**“Nothing much, really.”** Rin shrugged, careless, like he was playing. As if to tease Samael, his tail flicked back and forth in a metronome, **“You put me to sleep with your seal and if I end up breaking free again in say, a week and a half, you don’t interfere.”**

His gaze shot from that tail to Rin’s face, feeling a warped grin split on his own at those words. 

“Oh?” He hummed the questioning sound out, curious to see what Rin would offer him in exchange, “that’s a weighty request, I hope you have something of equivalent value.”

That got a beaming smile from Rin, reminiscent of his human half, if one ignored the blood staining his hand that he hadn’t burned off once the ice had melted.

**“Sure I do,”** Rin said, leaning back on the edge of the bed and cocking his head. Warped flames spun in his eyes still, as captivating as his tail, **“If I** **_don’t_** **end up breaking free by that point, I’ll be a good little demon and follow your stupid plans until whatever happens to break me out of this pathetic mortal cage happens.”**

Rin leaned forward with a smirk and a dangerous glint in his eyes as if he thought the whole wrench his early appearance had thrown into Samael’s plans was the most exciting thing that had ever happened to him.

**“How about it Samael? Do we have a deal?”** He held out a clawed hand, pinning Samael with that flickering gaze as his smirk turned into a fang-filled grin that seemed to say that this was all going according to plan. His plan.

Mephisto met that gaze with his own smirk as he took Rin’s hand. He could feel the energy running beneath his skin, remembered the burning ice.

Then he shook that hand.

“Deal,” he pulled his hand back with a slight scraping of claws along pale blue veins, “It will be quite interesting to see how you intend to break through my seal, Rin.”

Mephisto winked, getting a wider smile from Rin at the action, the little imp humoring his quirks, no doubt, “I’m well known for my seals, after all, and the original one has worked pretty well, all things considered. Think deeply on who will be caught in the crossfire, though, you may regret being too enthusiastic about breaking free around delicate beings- your _friends_, for instance.”

With that final word of advice, Mephisto stood up to get to work with practiced ease and efficiency. Rin flopped back onto his bed, white hair spread on his pillowcase and getting comfortable with a stretch of his neck to either side. As expected, Rin fell asleep as that white hair faded to inky black, his claws receded and his elongated fangs and ears became nothing more than little points. Mephisto let out a breath at the exertion that he didn’t know he was holding before double checking the seal and turning to walk away with a playful smile playing on his lips.

_‘I look forward to seeing how you break out of this one, little brother.’_

§§

The next day had Rin walking into morning classes more awake than he had been in weeks and he actually paid attention for once! Sure it was still kinda hard to follow along in his history and maths class but without a lack of sleep plaguing his mind, it was definitely a hell of a lot easier to pay attention to the subjects. 

He honestly had no idea why everything changed when just yesterday he felt like he could collapse at any moment from sleep deprivation but he wasn’t one to look a gift horse in the mouth. 

His good mood certainly didn’t last though, as right before lunch he started feeling sharp pains in his gut and he felt more hungry than he ever felt in his life. Along with the sharp pains, his senses started going haywire. Rin kept losing his balance and bumping into stuff, he would smell and see things that weren’t there and he was burning up. He wondered if it was a demonic thing or he was just going crazy because he’d never felt like this, even when his flames ran rampant.

It made him miss the sleep deprivation. But even just thinking that had Rin biting back a whine of frustration because the remembered agony of the dreams and the misery he’d been dealing with struck through that thought. Which was worse? Moving in a constant haze or burning with the jolts of adrenaline spiking his pulse through the roof?

Was it something wrong with him physically? Something a doctor could treat? But they could barely afford groceries, did he have the funds to see a doctor for this? What would he even tell them? ‘Hi, I’m a half-demon spawn of Satan having vivid hallucinations that follow me out of my dreams and I haven’t slept in weeks and now it feels like my flames are trying to push through my skin. You got pills for that?’

A laugh bubbled past his lips and he realized it may have been a bit hysteric by the wary looks the other students nearby gave.

There was, of course, one person who wasn’t really a person, knew he was the spawn of satan, and controlled his allowance, who he might go to for help. Rin wasn’t sure if the cost that came with the help would be worth it.

_‘Maybe I should go ask Mephisto if he knows what’s happening to me cuz this is freakin’ ridiculous. Ughhh, my shirt is glued to my back with sweat for fuck’s sake! I’m hungry but ugh…I need a shower before cram class and maybe a nap will help me feel better…’_

His thoughts rambled, the pressure under his skin sending him to scratch at his arms it reddened, healing each time in useless expenditures of energy that did nothing to help.

With a final growl to express his frustration, Rin fled from the cafeteria and headed back to his dorm. He was somewhat thankful that Yukio was still on his mission because that meant he didn’t have to answer any questions, or lack thereof, from him. 

When he’d woken that morning, refreshed and energized, Rin had realized that not only was Yukio gone, he hadn’t really been present at their shared dorm for weeks now. It twisted his heart, two sides warring in his mind. 

Yukio’s absence hurt. They were all they had left, after dad. In all of the craziness of their lives they were supposed to have each other’s backs. But, instead, he seemed more distant and distracted, even on the occasions he was home, which concerned Rin. But the other half of the warring sides thought, when his nerves were frayed like this, it was better that he was alone so he didn’t have to worry about lashing out at anyone. 

It wasn’t long after he got back to his dorm that he was under scalding hot water from the shower. Rin sighed in relief when he felt all the tension that he didn’t realize had built up fall away as soon as the water touched his skin. He winced when he straightened out all the kinks in his tail from having it wrapped around his torso all day and he reached back to lather the appendage with shampoo as well as to get any tangles out of the furred tip.

Exhaustion quickly overtook him when he stepped out of the shower and stumbled his way to his room with only a towel around his waist. He was out like a light before his head even hit the pillow.

§§

Darkness surrounded him and he breathed a sigh of relief when he didn’t see or hear Him anywhere in the dark abyss.

Something was wrong though, a sense that he was forgetting something important. A threat.

Who was he supposed to fear? Why did it feel so familiar, haunting the corners of his mind, like it twisted and writhed just outside of his peripherals. Now that he dreamt, free from the distractions of the waking world, his failing memory screamed for attention. 

Rin failed to notice a figure, failed to notice as _He_ watched Rin with a smirk on His face as He thought about ways to break out of Samael’s accursed seal. The earlier pressure He’d exerted on the body they shared- on _His_ rightful body- had done its job, wearing on Rin’s nerves like a constant gnawing itch. _His_ smirk quickly formed into a fang filled grin as an idea came to _him._

**_‘He may be able to resist_** **me** **_but can he do the same for his dear, baby brother?’_**

With relative ease, _He_ changed _His_ form to look like Yukio and made it so that _Yukio_ was trapped by thick ropes wrapping around his form.

Then, Yukio began to scream.

“Niisan, help! It hurts, niisan, please!”

At the sound of _Yukio’s_ voice, Rin’s head snapped up and he started running towards where he hoped his brother was.

“Yukio? Yukio where are you?! How the fuck are you-“ His voice caught in his throat and wide blue eyes widened as he took in his little brother’s quivering form trapped by thick strands of rope pulled taut until it looked painful. Ugly purple bruises colored his skin where the rope bit into flesh

“Y-Yukio? Wh-what happened? Why are you here? Why are you trapped? Oh gods, how do I help?” Questions rolled off his tongue as thoughts flitted through his mind a mile a minute and he knelt in front of _Yukio_ while reaching a shaking hand towards him- if he could just burn the ropes off!

_Yukio_ seemed exhausted as he tried to lean towards Rin and he could see the dark rings under his little brother’s eyes. The sight made his heart clench and he wracked his brain on how to get _Yukio_ out of those damned ropes. _His_ voice was nothing more than a whisper and he spoke through panting breaths almost as if he’d exhausted himself by screaming for help.

“I don’t…I don’t remember. The last thing I do remember…is that, that damned demon knocking me out and then I I woke up here. L-like this.” His brother, usually so strong and hating to show tears, even though he’d been such a crybaby as a kid, let out a pained whimper. It tore at Rin, making his efforts to free him frantic.

Rin had started tugging and pulling on the ropes while _Yukio_ was speaking in hopes of loosening them but they only seemed to tighten which made his little brother gasp sharply in pain. It didn’t make any sense. What could they be made of that he couldn’t tear apart with the superhuman strength he possessed? He was forced back as more rope appeared out of the shadows, attacking him while beating against Yukio and leaving bright red welts in vivid lines against his pale skin. 

His brother seemed resigned to his fate as he tried to motion with his hands for Rin to leave but Rin just shook his head while moving closer to _Yukio_ and using his flames to burn away the attacking ropes. His eyes lit up with determination and an idea while looking at his brother.

“My flames! My flames work against the ropes! Hey Yukio, stay still while I try to burn these ropes ok?”

The idea seemed obvious and Rin couldn’t understand why it had taken him so long to remember his flames. Another blip in his memory he ignored to focus on the present.

_Yukio_ looked up at his brother as fear flashed in his eyes before resignation took hold and he bowed his head, exhaustion making his words rasp from a throat he’d screamed raw. “Rin, you can’t- you can’t use those so recklessly. You _can’t_ rely on them, they’re too dangerous. Remember what I told you. _Please._”

Rin stared, forlorn, up into the tears staining Yukio’s cheeks before reaching out to gently squeeze his brother’s shoulders and forcing _Yukio_ to look at him.

“You know I can’t do that, Yukio. I’m supposed to watch out for ya, remember? And I won’t let _anything_ happen to you. When we get out of here I swear we’ll go track down and kill that damned demon together ok? Will you trust me?”

_Yukio_ went quiet for a minute while looking at Rin as if searching for any hint of dishonesty. Another sharp gasp tore itself from _his_ throat as the ropes tightened again around his form and the sound of bones cracking under the pressure made Rin tighten his grip on his brother’s shoulders.

Desperation welled up inside him, begging with Yukio- why was he being so _stubborn_ about this? Why did he always have to fight Rin on _everything?_

“Please Yukio. Just this once, please let me help you and I swear that I won’t use my flames recklessly ever again. I-I can’t lose you Yukio…not after dad. You’re the only family I have left.” He gasped through the sobs wracking through his body, unable to understand why Yukio kept denying him when he was trying to save him, dammit!

_Yukio_ let out a strangled breath and finally met Rin’s gaze fully, “O-okay niisan. I trust you. You better…you better keep your promise.”

Rin let out a nearly delirious huff of laughter before hugging his little brother, careful of the ropes,and then he began burning them, blue flaring around their bodies to chase the darkness away. 

With Rin’s head tucked into the crook of Yukio’s neck, he failed to notice the smirk on _Yukio’s_ face as he watched the ropes start to charcoal, cinders rising in the void with each strand destroyed.

** _‘Heh. This is easier than I thought. Poor little Rin, it looks like your heart is bigger than your brain, but for that I’m thankful.’_ **

It wasn’t long until one of the thick ropes completely burned away but it was then that Rin felt a pull and something within his mind forcing him awake. He jerked his gaze back to _Yukio_ flaring his flames higher, terrified that he would get torn away before he could free him from his bonds 

Yukio just smiled at the expression he wore, leaning his forehead against Rin’s .

“Don’t worry, niisan, you did good. Look, there’s already one gone,” his neck had been freed, that was true, but the broken bones in his wrist had Rin whimpering, shaking his head as he tried to cling to Yukio, to stay..

“How can you say that? I can’t leave you here!” Rin shouted, clawing at the ropes that resisted his flames with a tenacity he couldn’t understand.

“You have to focus on yourself, Rin,” Yukio sighed, seeming to ignore the panic in Rin and the pain in his own limbs to chide him, “look at how much class you’ve already missed, and don’t think I haven’t noticed the homework piling up on your desk.”

Despite himself, Rin laughed out loud, scrubbing at the tears in his eyes in incredulous humor, “Are you kidding me, Yukio? You’re worrying about _my_ health now?”

The pull started to overwhelm his attempts to stay, no matter how hard he struggled. Rin lashed out towards Yukio, knowing he didn’t have long.

He pulled _Yukio_ in for another distraught hug, whispering promises to come back for him, that he wouldn’t leave him here, he’d be free soon. 

Then everything would be okay. 

Rin’s figure vanished as he woke up, leaving Yukio in the void.

_Yukio_ faded back to _Him_ as the ropes disappeared and he stretched his mimicry of aching muscles.

**“Hmph. What a** **_child._** **He makes it so** **_easy_** **to manipulate.”** He crooned his words to the abyss, a taunt, **“just you wait, Samael, I’ll get out of here before you know it.”**

_His_ dark laugh echoed long after he’d disappeared.

§§

Rin awoke with a sharp pain in his gut as his hunger came back with a vengeance and he glanced at his clock. A sense of urgency pressed at his mind but, when he tried to grasp at why, it unraveled.

_‘Still have an hour and a half left to eat and get to cram class. Thank gods’_

He didn’t have the money nor the patience to deal with people down at the cafeteria so he trudged down the stairs to the kitchen to see if there was something quick he could make. The steps jarred at him and he winced in pain as a wave of white hot agony seemed to envelop his gut and he clenched his teeth to hold back a strangled cry. 

Rin breathed a sigh of relief as he finally made it into the kitchen and opened the fridge. He ignored his shaking hands, digging around until he found pork cutlets. It might not have been the quickest option but Rin found himself unable to resist, the urge to get his teeth on the red meat making all other possibilities obsolete.

As if to force the urge, more waves of pain made him wince. brought down the knife with more force than necessary, slicing through the raw meat and making blood splatter on his face. 

Dropping the knife in a clatter to the cutting board, he looked down at the slab of meat and brought his shaking fingers to his face. He gasped as he took away his fingers that were now covered in blood. 

A surreal mood overtook him, then. He should be washing the blood from his fingers and getting back to his lunch. Should be. 

His mouth filled with hot saliva as his vision narrowed on the red staining his now clawed fingers. The scent of it filled his senses and his stomach clenched painfully with sudden need.

The sound of his heartbeat thudding to his chest mirrored the spreading haze in his mind.

As if in a trance, he brought his fingers to his mouth, his newly tapered tongue lolling out to wrap around the digits and he started sucking with a need that he never knew existed within him before. 

A deep moan left his lips as he grabbed the raw slab of meat with his other hand and brought it to his mouth. Fangs lengthened behind his lips as he removed his fingers, now clean of blood, and tore into the meat with a snarl.

Rin didn’t notice as he swallowed blood and flesh that his hunger was slowly fading away and he was too lost in his clouded mind to register that both Kuro and Ukobach shared worried glances before watching Rin devour the meat with carnal viciousness. 

Blood covered his hands and mouth as he tore into the flesh like a starved man in front of a buffet. until, with a shuddering whine, he realized he’d finished. Licking his fingers and mouth clean of that addictive taste that he couldn’t seem to get enough of, he growled as he finally noticed the presence of both familiars in the room. Leaning back into a crouch, he bared his fangs at them both and _snarled._

**“Give me** **_MORE!_****”** Rin’s dark aura filled the room and his eyes warped with blue flame while red irises narrowed into slits. His tail lashed wildly behind him and he snapped his head towards the kitchen familiar when Ukobach let out a terrified squeak and tried to run away from the hungry, more powerful demon. 

Like prey, fleeing. His eyes flashed dangerous blue heat as they followed the scurrying creature, making a move to lunge and trap the poor familiar but was caught under a full-sized Kuro who roared and snapped his fangs in front of Rin’s face. He immediately started thrashing and snarling as he tried to break free but fell limp when he found that the cait sidhe wasn’t going to budge.

_“Rin, it’s me!!! Please don’t lose yourself again! Come back, please!”_ With another pleading roar, it was like a switch flipped and Rin’s eyes began to clear.

Flames dwindled in his eyes as he looked up at Kuro with horrified shock. His claws turned back into blunt nails and his fangs shortened to smaller points in his mouth while the cait sidhe shrunk back to the size of a normal cat.

“K-Kuro? What…what happened? Why am I on the floor?”

Kuro’s ears flattened to his skull, wary, and his eyes narrowed in bewilderment. _“Do you…do you really not remember Rin?”_

At the fear he saw there, Rin shook his head, unsteady as he tried to understand why Kuro would look at him like that. It scared him, how Kuro flinched when he sat up. But he didn’t run from him, allowing Rin to cradle him in his arms as he started purring in comfort, whether for himself or for Rin, it was hard to tell.“ I don’t remember anything, Kuro. Just making pork cutlets and then I must’ve blacked out from this weird pain I’ve been having. Did anything happen after that?”

The cait sidhe held his gaze for a long while, as if searching for something in the depths. Before Rin could really start to worry, he purred again and rubbed his head to his chest, “_No, nothing happened. I just…I just got worried cuz you wouldn’t wake up.”_

Something still sounded off to Rin. 

But, before he could question his familiar anymore, he glanced at the wall clock, jolting to his feet with a loud string of curses. “Fuck! I’m gonna be so late! Oh man, Neuhaus-Sensei is gonna kill me! I’m sorry for scaring you, Kuro, I’ll see you after class!” 

He was out the door before Kuro could respond, promising himself that he would try to figure out what was worrying him when he got back. 

§§

Rin sighed in relief when he saw that their teacher wasn’t there yet and slumped against the door to catch his breath. He didn’t notice the others, especially the Kyoto Trio eyeing him warily as he went over to his chair and unceremoniously plopped down and lay his head on the table without a care. 

Weirdly enough, despite the rush that had left him without lunch, Rin felt kinda good. Though, something about that didn’t feel right either. The pork was gone when he came to, so maybe he did eat and just didn’t remember? He felt full and there were no more searing pains in his gut, at least. Whatever, no point in thinking about it now.

“Rin? Are, are you ok?” Shiemi’s timid question reached his ears and he opened an eye to see the she was reaching out towards him only to quickly pull back when she noticed him looking.

That didn’t make any sense. Or it made about as much sense as Kuro’s wariness from earlier. Rin wanted to shake someone in frustration. Why was this happening to him? Why now, after it seemed like he’d finally begun to make friends, finally started doing something that might have made his dad proud?

Sitting up and turning towards her with a small grin on his face, trying to keep the worry in her eyes from worsening as he scratched at the back of his head in a sheepish motion.  
“I’m fine Shiemi. Just ran all the way here, that's all. Heh I overslept again I guess.”

There was no need to tell her or anyone what might or might not have happened when he blacked out earlier. It would just make them worry more. If it happened again, he’d make sure to tell Mephisto- or somebody. 

She seemed to buy his placations and responded with a hesitant smile of her own as she reached the rest of the way to grab his hand.

“Alright, Rin. You know you can talk to me about anything, right?” Shiemi looked up at him with a hopeful glimmer in her eyes and the sight made Rin blush a little before looking away, noticing that she still held his hand.

“I, uh, yeah, Shiemi, I know. T-thanks.” The blush grew deeper on his cheeks to the tips of his ears as he gently removed his hand from hers. He couldn’t help but breathe another sigh of relief when Neuhaus-Sensei walked in with his usual glare, effectively shutting off any further conversation.

_‘Damn that was awkward…’_ Without another thought, he opened up his demon summoning text and began reading along while Sensei spoke, failing to notice a certain brash exwire glaring holes in the back of his head.

Maybe things weren’t so bad if Shiemi could still hold his hand like that.

**Notes for the Chapter:**

> The twist on Rin’s abilities is just an hc that I have and I hope y’all like it  
I wanted him to be different than Satan ability wise and I thought this was a good way to do it  
Also about the ropes around “Yukio”, each of them represents a more demonic attribute that when burned away, manifests itself back in Rin


	4. Demonic Babysitting In All It's Glory

**Notes for the Chapter:**

> i hope ya'll enjoy~

As soon as Rin fell asleep that night, he was once again greeted with the rope bound form of _Yukio_. He started to panic when it looked like his little brother wasn’t breathing or moving and he ran towards him to grip his shoulders in fear.

“Yukio? H-hey, it’s me. Come on, wake up”

No movement and it was only then that Rin noticed the cuts and bruises covering his _brother’s_ face. He traced shaking fingers over the vivid marks, his other hand moving to take the limp fingers of Yukio’s where he was still bound at his wrist.

“Yukio?! Please wake up! I’m sorry that I couldn’t get here sooner but _please wake up_. I can’t lose you, too.” He bowed his head as tears gathered in his eyes and so missed the way his _brother’s_ face twisted into a malicious grin filled with too many teeth.

He pleas worked, Yukio twitching beneath his hands into waking.

Yukio’s hand weakly pressed to Rin’s in a reassuring grip as he made soothing sounds.

“Shh, I’m ok nii-san. I just fell asleep, that’s all. It seems that the longer I’m in this place,” he nodded vaguely at the seemingly endless void around them, “whatever it is, the more energy I seem to lose. I don’t know how much more time I have.”

Rin didn’t really understand- but he didn’t understand how Yukio was in this horrible place to begin with. He nodded as if he understood anyway, not wanting Yukio to have anything else to worry about. Their eyes met in a silent agreement that they’d both get out of here as soon as possible and, with an unwavering smile from Yukio, Rin began burning away another thick piece of rope.

“I won’t leave you here, Yukio,” Rin spoke the grim promise, watching his flames from a furious gaze beneath heavy brows.

“I know you won’t, Rin.”

§§

Unlike last time, it seemed to take longer to burn away the rope and it wasn’t long until Rin felt the familiar tug in his mind telling him that it was time to wake up. Rin started to panic and looked up at his twin who had that same unwavering smile.

“Don’t worry, nii-san. I’m not going anywhere and you can try again next time.”

The tug in Rin’s head grew painful as he furiously shook his head and more frustrated tears gathered in his eyes. He gripped Yukio’s shoulders and looked into his eyes with steel resolve.

“No. I’m not gonna leave you until I get this damn rope off. I don’t care how much it hurts, Yukio, it’s not happening, not this time.” He then looked at the rope that mocked him with its presence and raised the already burning temperature of his flames. 

Careful focus- focus he struggled to achieve in most every other aspect of his life- let him keep from burning Yukio and train it all on the rope. He hollered out a ‘yes’ when it finally burned away, leaving only two thick strands of rope binding Yukio.

He went to hug him only to be physically _yanked_ back from an invisible force and the pain in his head worsened. So close! He was so close. So why? Why did he have to wake up? Rin’s eyes watered, the liquid obscuring Yukio’s weary ones until they almost looked like warped versions of his own. Yukio shook his head slowly and smiled at Rin.

“It’s ok, nii-san. You need to go back now, I’ll still be here ok? I promise nothing will happen while you’re gone.”

His words put Rin’s mind at ease as he returned Yukio’s small smile with one of his own, forced wide and cheerful so that Yukio wouldn’t be worried about Rin.

§§

Rin woke up to bare walls and an empty room. Kuro was nowhere to be found which made Rin wonder why the cait sidhe has been avoiding him since yesterday.

_‘Something must’ve happened when I blacked out that he’s not telling me. It still makes no sense that he would purposefully avoiding me though, even after whatever happened.’_

He pondered about what could’ve happened until an all too familiar pain made itself known deep in his gut and he sighed.

_‘Well, at least the pains aren’t as bad as yesterday. Still, I guess I better make myself something before cram tonight…’_

Heading downstairs, Rin noticed that Ukobach wasn’t in the kitchen and his absence made a pit of worry form until it settled in his gut like a stone. It was extremely odd for _both_ familiars to not be around, so, putting his stomach pains aside, Rin started to walk around the whole dorm trying to pick up either familiar’s scents and, with each passing minute of not picking up anything, the pit in his stomach grew. But, eventually he had to give up or risk getting put out of commission by the hunger pangs. 

It hurt. Rin stood back in the kitchen and confused tears began gathering unbidden in his eyes.

_‘Why are they avoiding me? Without Yukio here, they were all I had...and now I’m all alone.’_

An all too familiar feeling started building up along with his worry and the next thing Rin knew, his fist left a sizeable dent in the freezer door.

_‘Fuck! Why is everyone avoiding me?! First Yukio, he started distancing himself months ago, blaming me for dad’s death, and now Kuro and Ukobach. I didn’t even do anything for this to happen goddammit!’_

With a start, he briefly cursed himself for ruining yet _another_ thing in his rage before looking at the clock on the wall and widening his eyes in panic.

_‘Great, now I have even less time to eat…’_

He’d have to make himself something quick and as much as he hated instant ramen, he grabbed a cup out of the cupboard with a sigh, forcing down the overly salted noodles that didn’t sit right in his gut. 

As he made his way to cram class, his mind was filled with thoughts of Yukio and what could’ve possibly happened yesterday to make both familiars avoid him like the plague. He couldn’t even focus with all the thoughts swirling in his head and the building pressure of an upcoming headache made him want to puke, not noticing the way everyone one in the classroom including the teacher looked at him in growing worry and a hint of fear in their eyes. 

But something did register. Something that wasn’t human. 

Someone.

A familiar scent, one that brought to mind shattered earth and overly-sweet candies, had Rin’s fangs extending behind his lips.

_He_ was here.

Earth.

Rin could feel his irises warp to blue flame beneath shuttering eyelids as he scanned the classroom for the source of that scent. 

A haze began to creep over his mind, called forth by the challenger in his vicinity. He remembered their last confrontation, remembered setting his flames on the embodiment of earth and delighting in his pained shrieks. It was only just, after-all. He’d tried to hurt what was Rin’s, had thought to challenge him and call him out.

Rin couldn’t remember why he’d hesitated to answer that call, now. 

He wouldn’t be hesitating this time. But, he _would_ wait.

So, when the teacher dismissed them, he stalked towards the back of the classroom to where Rin could practically _feel_ that uninterested gaze burning holes in the back of his head. 

Gold eyes stared at him, unabashed by the threat bearing down on him as he lounged with his feet up on a desk. Rin didn’t question how he’d gone unnoticed by the rest of the class, didn’t care. 

A low growl, too low for the few lingering students in the room to hear, rumbled from his chest. Those pointed ears twitched to hear the sound. The look in those eyes never changed, even as Rin grabbed the collar of his maroon coat to tug him forward.

Rin would find out what he was doing here. Then, he would get him out of his territory.

§§

“Why are you here?” Rin hissed out the question like it was poison on his tongue as his disinterest turned into amusement at Rin’s tone.

The fury that burned in Rin had Amaimon perking up, tilting his head despite the hands holding him as he considered whether Rin might want to play with him this time instead of resisting like he had last time.

“Big brother wanted me to watch you for any signs.” Amaimon’s bored tone betrayed the emotion that bubbled in his chest but his answer only seemed to make the grip Rin had on his collar tighten. Then he shivered as he felt the familiar pinprick of claws digging into his skin from where Rin gripped his shoulder with his free hand.

The feeling made a grin break out on Amaimon’s face and he brightened as he leaned closer into Rin’s space. Though it was difficult with the way Rin refused to let him move from the half-coiled position in his seat. 

“But, if you want to play, then it’s not _my_ fault” With a quick snap of his fingers, Amaimon was out of Rin’s bruising grip and running from the room with a taunt, “please don’t be as disappointing as last time, Rin.”

He fled, fangs bared in a wild grin as he felt that powerful presence chase close behind.

Maybe his task would prove more entertaining than he’d first anticipated..

§§

Rin turned around and, unbeknownst to him, his eyes narrowed into slits within warping blue flame as he tracked his fleeting prey. 

With a feral growl that made the remaining humans startle and cower in fear, he was out the classroom door. It wasn’t important. All he could focus on was the quickly retreating form as he ran past the bounds of the school, taking a familiar path towards Rin’s territory, his dorm. 

Trees, rocks, and underbrush all became a blur and Rin could feel his flames roaring to life under his skin, begging to be free and, in his instinct driven mind, who was he to deny the all-consuming fire?

He bore down on the challenger, determined to answer the question he’d been asked in their confrontation. Who would be predator and who would be prey?

Another burst of energy just as they neared the vicinity of his dorm and he pounced, tackling the lithe body to the forest floor in a vicious impact that cracked bones. He snarled down into the face that had mocked him earlier, watching those slit pupils sliver, lost in the gold of his irises. 

His elongated fangs snapped inches from the face staring up at him, dripping with saliva as sharpened claws dug into fragile skin. But, even when faced with the punishing glare in front of him, all he got for his efforts was a playful grin that stretched his lips wide as he bared his neck in an arrogant display.

As if he wasn’t at his mercy, as if he was _happy_ to be there.

**“What do you think you’re doing, Amaimon?”** Rin’s voice was anything but human as he spoke and the power and authority laced in his tone sent shivers down Amaimon’s spine. Rin felt them and dug his claws in further to elicit a hissed breath.

“Oh? I didn’t think you’d remembered my name.” Memory had nothing to do with it. The concept of earth only had one true name and he could taste the syllables of it on his tongue just as surely as he knew the scent of him. “I just wanted to play with you again. It was so _boring_ watching you all day, little brother, and you seemed restless so I thought I might help.” 

Amaimon’s nonchalant attitude ground on Rin’s nerves and the longer he looked at his bared neck _so close_ to his aching fangs, the more he felt that familiar pang of hunger settle deep within his stomach.

The haze clouding his mind grew stronger as he leaned closer and closer to the tantalizing throat offered to him so willingly. Hot saliva pooled in his mouth and he licked his fangs, the sound of his pulse thrumming in his ears until he let his now tapered tongue trace the lines of those delicate veins. 

Amaimon’s pulse picked up and he arched his neck towards Rin’s needle-point fangs as if he wanted nothing more than for them to bite down. Rin, lost to his instincts and the hunger washing everything else away, answered Amaimon’s advances with a deep purr as he sank his fangs into the artery. 

As soon as that warm liquid started pooling in his mouth he swallowed. A blazing heat gathered in Rin’s core and he started trailing his claws over Amaimon’s front, tugging on his clothes while his fangs dug deeper into flesh, ripping the skin and allowing more blood to flow freely down his throat.

Rin snarled against Amaimon’s throat as his claws tore away clothes and flesh awhile Amaimon purred as his hips moved to grind against Rin’s, his hardened cock already leaking precum in his pants. 

The smell of blood and growing arousal hit Rin’s nose and an answering purr rumbled deep within his chest as his hips met Amaimon’s with growing desire before his claws tore away Amaimon’s pants, releasing his twitching cock. 

A serpentine tail moved to wind itself around Rin’s leg as his claws gripped Amaimon’s thighs in a bruising hold before he set his fire to sear the clothes from their already heated bodies. Rin wrenched his fangs from Amaimon’s throat and stared into glowing golden eyes that followed the blood trailing down his chin before leaning up to capture his lips in a forceful kiss. 

Elongated fangs bit into Rin’s bottom lip drawing more blood as their tongues wound around each other’s in a fight for dominance. Deep moans were swallowed between them as Rin’s tail shot up to wind itself around Amaimon’s neck and squeeze, leaving bruises that quickly healed. 

He growled as he felt Amaimon’s tail slide in a rasp of scales over his body, drifting down to beneath the base of his own tail before it moved to Rin’s entrance. 

The tip teased him and made Rin shiver, pressing back on it as a molten heat built in his core and he broke the kiss to whine into Amaimon’s ear.

**“Amaimon** **_please._** **I want- I** **_need_** **y-.”**

A broken cry left his lips as Amaimon’s tail forced itself into his entrance without warning and started thrusting while Rin’s cock left trails of precum on his skin as each thrust rocked his body. 

Warped irises met glowing gold as Rin locked eyes with Amaimon and dragged his claws down his torso, leaving deep gashes against pale skin and covering his claws with blood and precum. Instinct had him bringing his fingers to his mouth, tapered tongue wrapping around each digit and licking them clean.

A switch seemed to flip as a sadistic urge flared in his mind as soon as that euphoric mix met his tongue.

Enough games. He’d show the earth king the meaning of the word “all-consuming.”

§§

Amaimon’s hips bucked up into Rin’s as lust began to cloud his vision, though he could make out the smirk that grew on Rin’s face as he ground his ass back onto his tail, taking him in deeper with each thrust. 

Rin’s tail tightened around Amaimon’s throat and his vision darkened as his vessel’s brain tried to cope with the lack of oxygen. 

Hands gripped his hips, bruises forming there when he abruptly felt himself get flipped on his hands and knees. Amaimon’s tail met with the cool breeze of the forest air and lack of warmth from Rin’s entrance as he tried to whine despite the building pressure on his airway.

**“That was fun, Amaimon,”** Rin leaned flush against Amaimon’s back as he whispered huskily into his ear, making him shiver at the guttural tone. **“Don’t you think it’s** **_my_** **turn now?”**

Amaimon keened and pushed his ass against Rin’s cock to convince him to stop teasing. That was all the answer Rin needed before he sharply bucked his hips, his dick pushing into Amaimon’s entrance with all the force of a semi-truck until he was deep as he could go. 

His claws dug into the skin of Amaimon’s shoulders, wasting no time to begin fucking into his body. He growled and hit Amaimon’s prostate, making him moan loudly as Rin’s grip turned punishing.

**_“Hnnnn..._****you’re so fucking- fucking tight, Amaimon~”** A deep purr that became a growl accompanied Rin’s words and Amaimon felt the vibrations against his skin making him lose himself further to the carnal pleasure.

The slick slapping of skin against skin along with the grunts and moans coming from their gasping mouths filled the quiet forest air and it seemed that hours passed by until they both came with a deep, guttural roar. The warmth of Rin’s seed as it filled Amaimon made him shudder before his arms gave out and he fell against the forest floor, his own seed covering the grass and leaves beneath him in a sticky mess. 

Hot breath coated his sweat drenched skin as Rin collapsed against his back. That breath made a sudden drop in temperature, cooling Amaimon’s flesh until he could feel the sweat freezing as tiny droplets. The abrupt shift made his heart jolt, trying to understand the strange sensation and unable to place it at first.

Gehenna. The heart of that mirror world to Assiah. Blue fire that made up existence, both creation and destruction. The coldest depths and flame so hot it felt cold.

But he didn’t have the energy to puzzle the phenomenon that was Rin Okumura just then. He snapped his fingers, placing them both on Rin’s small bed in his dorm a moment later. 

Amaimon watched with fascination as elongated claws and fangs receded back until they were nothing more than tiny points in Rin’s mouth and weak human nails on his hands. Still, he had taken Amaimon with all the ferocity his demonic heritage granted him and Amaimon would reward that. As he drifted to sleep, drawing his claws through inky black hair, only one thought stayed in his mind.

_‘This should be fun.’ _

And Amaimon made up his mind to not tell Samael in hopes that he and Rin would be able to play again.

Samael should have been more specific in his request if he didn’t want Amaimon to find a loophole.

§§

Rin awoke to clawed fingers carding through his hair and he yelped, almost falling off the bed in surprise, only to see Amaimon’s amused golden eyes. 

“What are you doing here?” Rin jerked his head to look around, just now taking in his surroundings. “And why are you in my bed?”

When all he was met with was an even more amused smirk from Amaimon and a sucker appearing that he brought to his mouth, Rin stumbled from the bed. He growled, confusion making his actions indecisive as he tried to figure out how the hell he’d ended up naked in bed with Amaimon. 

His tail lashed behind him to mirror his panic. Then Rin noticed the slit pupils of Amaimon’s eyes flick as if he tracked the erratic movements. But something else had just become apparent to Rin with his brain back online. 

Now, fully awake, he saw the blood, grime and sweat coating their bodies and his bed.

“I’m going to take a shower, dammit,” Rin hissed at where Amaimon watched him have his panic attack as if it were the most interesting thing in the world, “_don’t_ follow me- and I want to know why you’re in my classes now and why the clown sent you to watch me.”

A hum answered his words, brow raised as Amaimon picked at one of the many new stains on his rumpled sheets. Rin didn’t care, too thrown off to think about what some of those scents mingling in the room smelled like.

He stalked from the room, glad he couldn’t smell Yukio for once because he couldn’t imagine what he could possibly say to him to explain what was going on.

Something about the thought of Yukio made him feel like he was forgetting an important piece of a puzzle. His heart twinged in dread and he shivered despite the warmth of the halls to the communal showers. It was too much to worry about. He had to take care of the mess first.

Water sprayed from the showerhead and Rin stepped under, glad to get whatever was sticking to his body off as soon as possible.

_‘Ew. What the actual fuck happened last night. I smell disgusting…’_

Scrubbing at what he could smell was definitely blood, Rin felt his thoughts spiral.

It was weird that he had absolutely _no_ memory of last night. 

Plus, that something he was supposed to remember about Yukio niggled in his head. He tried to think about it more as a glance of what could’ve been a memory flashed to the forefront of his mind.

The memory was accompanied by searing pain which made him almost keel over, hands coming up to cradle his head as he let out a sharp hiss.

_‘Ow damn…ugh, what the fuck?’_

Rin managed to stand up on trembling legs long enough to finish his shower and the scalding hot water relaxed him if only for a bit. Tension Rin didn’t realize he had washed away under the water with each passing moment. He let out a sigh as he leaned his forehead against the wall, the damp tile a welcome relief to the now ever-present headache that seemed to pop up out of nowhere. 

Then it registered that he was no longer alone in the showers.

A hand pressed to his forehead and the ache in his skull faded in such a wash of relief that Rin gasped, eyes shooting open to stare blindly at the tiles.

“Wha-?” Rin tried to speak, breath cutting out as wiry arms snaked around his waist from behind, lean body sliding along his while a disorientated blush rose to his face.

“Amaimon!” Rin shouted, voice cracking and blood rushing in his ears as he tried to turn in the embrace. He met resistance until his continued struggles made the grip loosen and he shoved back to the tiles, staring into curious gold eyes from way too close.

“Are you done yet? I’m bored and you’re clean now,” Amaimon said as if he couldn’t understand why Rin was taking so long.

“What the _fuck_, Amaimon?” Rin growled, noticing the filth still covering Amaimon- and now him too, again, seeing as there was exactly zero room between their bodies. “I told you to leave me alone in here.”

Amaimon tilted his head, “you were just standing here, you weren’t even washing yourself, do you not know how?”

“What?” Rin glared, of all the stupid- “yes, I know how to wash myself. And it’s none of your business what I’m doing in here, dammit.”

“Hm, if you say so,” Amaimon shrugged, the movement sending more of the trails of dried blood wetting under the spray to sluice down his body. 

“Do you know how to wash yourself, even?” Rin couldn’t help the question. Seriously, who was Amaimon to ask him that if he seemed totally content without showering.

“And let go!” Rin said in a snap of fangs, irritation growing when Amaimon frowned and tightened his grip, “take a shower now that you’re here and then you’re going to start talking.”

How was this his life? If Amaimon didn’t listen this time he would get violent- was confused about why he hadn’t yet. Something held him back from lashing out, though, and Rin was too off-balance to question it just then. He needed space to think about things, but first he needed answers.

Another shrug and finally those arms released him, claws tracing over his wet skin and making him shiver with a harder glower to the impassive stare he got back.

It shouldn’t have been as hard as it was for him to take his gaze from the green tail that swept behind Amaimon as he moved to the next showerhead. Rin shook himself, mood worsening as it seemed like, without Amaimon nearby, his headache had returned. That was dumb. Amaimon _was_ the headache, not the cure.

He tried to tell himself that as more of the evidence of their _whatever_ they’d done washed from Amaimon’s body. Murky lines ran down the contours of his back and down his tapered waist, tracing along his calves to pool at his feet until Rin realized he’d still been staring.

Rin jerked his gaze away, scrubbing the bit that Amaimon had rubbed on him with soap in harsh movements until his skin pinked and all traces had been removed.

The room echoed when he turned the shower off in a squeak of the knob, simultaneously facing Amaimon and trying to ignore him as he toweled off. Then, looking to see Amaimon had elected to forget a towel for himself, tossed his at him, “I only brought one, use that.”

Amaimon did without a word and Rin huffed, collecting his shower supplies and heading back to the room. The whole way, his spine itched at having Amaimon at his back. But Rin didn’t care, was too stubborn to admit he wanted to keep Amaimon in his line of sight. If Amaimon wanted to attack him, he would have done it already.

Slamming the door with a bit more force than he’d intended only flustered Rin. He rummaged until he found his uniform and shoved it on, turning to Amaimon after he was fully clothed.

“Do you want somethin-” Amaimon cut his question off with a snap of fingers that clothed him in a half-assed modified version of their uniform. If Rin were less peeved he would have thought Amaimon looked cool in the fingerless gloves and tight, striped black shorts that made it to his knees, ending at a pair of heavy black boots. 

“Never mind,” Rin grumbled. He shoved past Amaimon again, knowing he barely had time to eat before class, let alone get answers, and determined not to go hungry this time.

All of this happened in silence, Amaimon apparently content to watch him like an animal in a zoo, waiting for him to do something “interesting.”

All he seemed to have in the fridge was leftover rice he somehow hadn’t eaten the day before and eggs. It hit Rin then that he didn’t know where Ukobach or Kuro were, hadn’t seen them since yesterday, either.

Rin faltered where he’d been making a quick meal of fried rice. His mood darkened, heart thudding in his chest to push the loneliness fighting inside him to the surface. Prickling at the corners of his eyes made Rin exhale in a sharp breath, not wanting to cry in front of Amaimon. 

Maybe they’d just left to restock the food. Yeah, that was it. 

He used that excuse, knowing it was flimsy, to finish breakfast, sliding the bowl to Amaimon with a sharp clack on the island counter.

“Talk fast, Amaimon,” Rin said, in no mood to play as he forced the rice down. For some reason it sat uneasy in his gut, though he had no idea why and ignored the feeling to stare Amaimon down.

Amaimon appeared to have no problems eating, a wide grin on his face as he inhaled the meal.

“Brother told me to watch you,” he said with a mouth full of food, uncaring that bits of rice fell out, “he said you needed help with your powers and I should be nearby.”

“Help,” Rin sputtered, trying to understand what about his powers he needed help with, “isn’t that what I’m at the Academy to do? Learn how to be an exorcist? Why do I need you?”

That got a glare from Amaimon, “the humans can’t teach you about your powers, you’re a demon.”

Oh. Those powers. That kind of help. Rin sank back onto his heels on the other side of the counter, picking at his meal, though he’d lost his appetite- if he’d had one to begin with.

“Fine, thanks,” Rin bit out, ducking his head to the side, “what happened yesterday then, why did we- why did I wake up like that.”

A gleam started to grow in Amaimon’s eyes and his lips stretched wider, “we played.”

“Play?” Rin repeated, baffled as his cheeks heated under the wicked cast to Amaimon’s expression.

He’d begun tracing his tongue to his fingers, cleaning the food he’d gotten there.

“Yes, play,” Amaimon said with a purr.

Rin’s grip on his chopsticks tightened until the flimsy wood snapped, breaking him from the staredown he’d been in and jolting him back to reality.

Reality being that he was most definitely going to be late again if he didn’t leave now.

“Shit,” he hissed lowly, scrapping the remainders of breakfast from his plate and washing it, unable to stop himself from the duties of kitchen clean-up after he’d built the habit. Though that just meant he was even more crunched for time as he darted back to the island to grab his bag and made it to the threshold of the kitchen, realizing he’d forgotten something important.

“Clean your plate, I don’t wanna leave a mess for Ukobach,” Rin ordered a nonplussed Amaimon, who’d been watching him run around with his chin in his palms and another sucker rolling between his lips.

Just seeing him so calm made the headache grow in Rin’s head, a flash of rage sparking in his gut. 

He left, not bothering to stay and see if Amaimon would comply and not caring if he followed. 

Maybe if Amaimon didn’t listen to him, disrespected the kitchen and stepped on Ukobach’s territory, the familiar would come back.

His headache worsened and Rin didn’t know if it caused his mood or was because of it.

§§

Rin couldn’t even focus in class, didn’t even have the energy to do anything except lay on the cool flat surface of his desk. The throbbing in his head kept getting worse with each passing moment and it made his senses all muddled, sights and sounds all meshing into one big clusterfuck. 

When the bell that signaled lunch rang, it made him grab his head and attempt to block out the shrill ringing with his hands, failing to notice had long since grown sharpened claws that dug into the skin of his scalp. The mind numbing pain was a welcome relief as Rin dug his claws deeper into flesh only to pull them back once he felt his hot, sticky blood coating his fingers and smelled the intoxicating scent. 

It permeated the room and filled his senses, leaving him in a drunken haze, not even noticing the sole remaining occupant in the room watching him as he chewed on his clawed thumb.

A tapered tongue rolled out of Rin’s mouth from behind elongated fangs and wrapped around his clawed digits before sucking and licking and losing himself to the intoxicating sensation of blood now coating his tongue. 

_He needed- needed_ **_more!_**

He briefly registered that the incessant pounding in his head had died down to where it became tolerable and he didn’t notice the clawed hand that now rested on his shoulder until he was on the floor _snarling_ and gnashing his fangs in front of Amaimon’s face.

Golden eyes met warped blue before Amaimon bared his neck in silent submission and it wasn't but a second later when those same needle point fangs dug deep into flesh, tearing away skin and swallowing spurts of blood. 

Minutes that could have been an eternity for all the attention Rin paid them passed until he was able to come back to his senses and realized where he was and who he was with. 

With a startled yelp, he moved off of Amaimon, uncaring about the blood coating his lips as he scrabbled away.

“Wh-what the hell?” Rin gasped the question, horror eating away at his sanity as he stared into Amaimon’s unrepentant face. A whimper escaped, “What the _fuck_ is happening to me?”

He felt like he was losing his _mind_.

No sooner had those words left his lips did it feel like someone stabbed his brain with a hot iron poker.

He couldn’t take it, Rin fell to the floor as unconsciousness claimed him and he knew no more.

§§

Rin cradled his head, letting out a blood curdling scream before collapsing and seizing on the floor. 

Amaimon honestly had no idea what to do. He’d thought things were finally getting interesting when Rin had pulled back and panicked. The situation was untenable but he couldn’t see a solution that didn’t involve Samael losing the bet with Rin. 

And he’d been expressly told that couldn’t be allowed to happen. 

Keeping Rin awake clearly hadn’t worked. Amaimon could see the flares of energy sending internal attacks directed at Rin and had tried to mitigate their effects. But unless he kept a hand on Rin at all times, the attacks would continue.

As he pondered on what to do, chewing at his thumb out of habit, Rin went deathly still and, when Amaimon looked closely, he could see that Rin was barely breathing.

Under his gaze, the core within Rin flared hotter.

§§

A seemingly endless abyss was the only thing that greeted Rin when he opened his eyes and he started to panic when he didn’t immediately find Yukio.

“Yukio? Yukio, where are you?”

How had he forgotten him earlier? His lack of memory throughout the day now clamored in sharp relief against his skull. Was it because of something Amaimon had done? Is that why he’d been unable to remember Yukio was trapped here?

Eerie silence was all that greeted him and tears began to gather in his eyes.

“Yukio _please_. Don’t....don’t leave me again.” Still nothing. Teetering between wobbling emotions had his terror replaced with rage as the promise they shared rang through his head mockingly. “Dammit, Yukio, we _promised!_ We promised that we wouldn’t leave each other again. So where the hell are you, Yukio?”

Rin could _feel_ eyes boring into him but he still couldn't see anything as he called out for his Yukio again and again until his throat felt raw and his voice was hoarse. Rin was left panting in the endless void.

Only then did he hear Yukio’s exhausted voice, full of accusation as he retaliated.

“_Leave_ you? I didn’t leave you Rin. It was _you_ who left _me_. You promised, you _promised_ that you wouldn’t leave me trapped here but you did, Rin. I stayed here for longer than I even know, _trapped_, while you were too busy with _Amaimon_! Need I remind you, _brother_, how he almost killed us just so he could _play_ with you?” Yukio’s voice rang through the darkness, an endless stream of condemnation, while Rin could only stand there and listen. 

Yukio was right, his words held no lies and each stabbed their way into Rin’s heart. His tears ran freely down his face but he didn’t bother to stop them, didn’t bother to stop the words spewing out of Yukio’s mouth like venom.

_‘He’s right....how could I leave my own brother like that? How could I even_ call _myself his big brother when I just left to do whatever the fuck I did with Amaimon last night?’_

Self-loathing welled up in Rin until he felt sick, until he couldn’t even _stand_ himself right then. He wasn’t even sure that he’d be able to look at Yukio in the eye. 

Imagining how Yukio must look right then, tears and blood and agony painting his face, had Rin shaking where he stood. 

What had all those times he’d defend Yukio when they were kids meant? What could his useless childhood brawls mean if he couldn’t do anything when Yukio really needed him, when the stakes were real? He’d long ago stopped caring if others called him a demon or a monster, he would suffer it for the rest of his life if it meant Yukio would be safe, if it meant he’d done his job as his older brother. 

And _nothing_would get in his way again.

Bitter determination filled him and he forced his body to stop trembling. Rin looked up from beneath his bangs into the endless abyss with one more promise, a _vow_, burning on his tongue.

“Yukio! I’m not gonna let anything stop me from freeing you, Yukio! Not even Amaimon, you hear me? I _swear_ it!” Rin yelled and let his unwavering resolve echo throughout the deep, dark void where his brother was trapped by some damned demon.

A familiar tug was all that Rin was answered with and he waited for a sign or anything from Yukio that would let Rin know that he’d been heard, but the all too familiar silence was the only thing that greeted him. 

With a final look around at the endless void, Rin stopped resisting the tug, closing his eyes to blink them open and seeing gleaming gold hovering overhead. 

If Rin had stayed longer in the void, he would’ve witnessed a malicious smirk that turned into a feral grin filled with too many teeth and warped irises of blue flame.

§§

Amaimon’s golden eyes narrowed on Rin, tracking him as he groaned and heaved his aching body off the floor. He swayed, rubbing at his head and leaning against the desk, much as he hated letting Amaimon see him in that weakened state. 

A clawed hand reached out to lay on his shoulder and it served to steady him, a wash of soothing relief bringing conflicting emotions out that Rin shoved down with ruthless efficiency. He couldn’t focus on that, not when he had to get Amaimon to leave so he could rescue Yukio before he forgot him again. 

Inhaling a deep breath, Rin shot Amaimon with a careful gaze. “Thanks. For that.”

“You’re welcome,” Amaimon said with a shrug, moving to press along Rin like a cat, “can we go now? I’m hungry.”

“Seriously?” Rin scowled and grumbled under the weight draped over him, “anyway, you were there this morning, you know there’s nothing to eat in the fridge.”

His pointed words only got a sniff from Amaimon and his nose shoved to Rin’s neck while they walked. Rin shivered at the touch, fighting not to tilt his head to give Amaimon better access.

Warmth pooling in his gut distracted Rin from the infant plan forming in his mind, not helped by the hands Amaimon traced in idle patterns over his stomach and sides.

“Dammit, Amaimon,” Rin said with a hiss of frustration once they’d exited the school and he saw the people milling around on their own ways home, “if you want to be helpful, why don’t you get groceries so we actually have something to eat?”

“We?” Came the guileless response, “will you cook for me again?”

“I don’t have time to get groceries and catch up on all my homework,” he snapped back, pulling away as far as he could from Amaimon to glare into his eyes, “so either you help me with homework or you help me with groceries. Your choice.”

“Hm, okay.” Rin held back the startled expression that wanted to form at the easy acquiescence from Amaimon, expecting more resistance and waiting for the catch.

“Cool, pick what you want and I’ll try to make it,” Rin said before he could change his mind and quickly pulled out his wallet for the grocery allowance from Mephisto.

The pleased smile lighting on Amaimon’s face had a curl of guilt twitch in Rin’s stomach, and a portion of his mind already ached in pain knowing that soothing touch wouldn’t be around to chase it away. 

But that regret was soon washed away, leaving grim determination behind, as Yukio’s words flitted through his thoughts. 

A snap and Amaimon vanished, leaving Rin alone in the courtyard.

Once he was out of sight and Rin could no longer smell his earthy scent, all energy seemed to leave him as he slumped, hands shaking on his knees to support himself there.

Forcing himself to take deep breaths and calm down, Rin slowly started making the trek back to his dorm, which was bare of any living being except for him, now. The pounding in his head threatened to knock him back into unconsciousness and Rin was quick to answer his body’s demands for sleep. 

Rin was in his room and in his bed before he knew it, the path he’d taken a blur in his mind and unable to even focus enough to take his uniform or shoes off. 

He didn’t even notice Kuro’s presence in the doorway, looking up at him with worry.

_‘I’ll find a way to help you Rin, I promise. Just please hang in there and don’t lose yourself. Don’t let him win Rin. I don’t wanna lose you, not like I did Shiro.’_

The cait sidhe seemed to vanish into the shadow of his room, on the hunt for anyway to help his only remaining friend.


	5. You Done Fucked Up, Yukio

**Summary for the Chapter:**

> Yukio fucked up. In the worst way possible

**Notes for the Chapter:**

> hiya it’s your old pal micchi here with another chapter~ we’re finally at the point where this was all leading to hehehehe and just a heads up, this chapter gave *me* the chills while writing it but AAAAAAAAA I’m so excited to share this with y’all and see your reactions
> 
> *rubs hands evilly* enjoy~

Rin awoke to the feeling of soft lips grazing against his before they pressed down with a gentle force. The smell of pine lulled him back to sleep until he noticed another scent mixed in. The smell of candy…? 

Wait, why would pine smell like candy? 

Heavy eyes filled with sleep blinked rapidly until the green blur in front of him became the clear figure of Amaimon. An all too familiar rage filled him when he remembered the other day, how he told Amaimon to stay away from him because he needed to save _ Yukio _ and he couldn’t do that with the freaking earth king following him around like a lost puppy. 

Speaking of the earth king, he was looking at Rin with interest gleaming in his amber eyes and that just began to piss him off more. Grabbing the hem of his slim jacket with clawed hands, a low and feral growl rumbled deep in his chest.

  
  


§

  
  


Amaimon didn’t even have time to widen his eyes at the sudden change in Rin before he was thrown back into the hall and through the wall into the bathroom. He could only watch as the younger demon was on him in seconds, gnashing his fangs in front of his face as his tail whipped about furiously behind him. The furred tip of his tail was wreathed in blue flames and Amaimon knew then that Rin’s demonic side was dangerously close to taking control again.

He knew it was better not to do anything that might set him off even more. So, with his gaze not leaving warped blue eyes, he craned his neck in a sign of submission and Rin immediately latched on to the pulsing vein beneath his flesh. His elongated fangs grazed the skin and all was still and quiet for a few moments before Rin licked his pulse and started purring. 

That settled, he closed his eyes and laid on Amaimon with a hum of contentedness, his tail wrapping around Amaimon’s and he inwardly sighed in relief as Rin’s features became less demonic. 

‘_ Big brother isn’t gonna be happy about this if he finds out… _’ Amaimon still debated on whether to tell Mephisto what was happening but his own curiosity won out in the end. 

Things were just starting to get fun. Amaimon decided to watch Rin for a little bit longer to see the outcome of the Mephisto’s little bet.

Rin sat up and stretched, yawning, while his tail whipped out behind him before curling up against Amaimon’s thigh, cat-like. Especially when he rubbed his eye tiredly with the back of his hand. A strange warmth tried to rise to his cheeks as Rin looked down at him with blue eyes empty of the threat they tended to carry in erratic intervals nowadays and tilted his head.

“Amaimon? What are you doing here? What time is it?” Rin asked between another yawn.

For some reason it was hard to speak. Amaimon cleared his throat before attempting again, letting the tile of the bathroom floor cool his body as it heated when he noticed Rin sitting on his hips. 

Then, utilizing the same indifference Amaimon had for thousands of years, he suppressed the reactions, thankful when Rin didn’t seem to notice his inner turmoil. “You wouldn’t wake up and I was hungry.”

Exhaustion seemed to weigh Rin down even though he’d just woken, eyes glazed and shoulders bowing as he processed Amaimon’s words. Lips parted like Rin wanted to respond before his gaze darted to the side. 

That demon lurking in Rin’s core, the one fighting past the weakening seal with growing ferocity every day that Amaimon watched, rose again. The piece of Amaimon that had spawned from that Gehenna flame wanted to know what would happen when the seal broke.

“If you’re so hungry then ask Ukobach to make something for you. I’m too damn tired to deal with this,” came Rin’s sudden words, blurting out of him even as his power welled further.

Though if Rin was talking about Mephisto’s familiar, then he must be more out of it than Amaimon thought. A moment later and Rin shook his head, the brief awareness making his mood sour as he mumbled softly, “_ oh… _”

It was like a switch flipped and pure, unadulterated rage erupted from Rin. His gaze hardened and warped as he looked down at Amaimon before wrapping a clawed hand around his throat. 

Amaimon couldn’t hold back the full body flinch as he once again felt Rin’s anger and aura becoming much like their Father’s and the movement made a predatory grin filled with too-sharp teeth stretch across Rin’s face.

“Oh that’s right. Those useless demons left so suddenly that I almost forgot they even lived here. Whatever, they can stay gone for all I care. It’s really too bad that I didn’t have a chance to hear their screams as I burned them alive for their betrayal, don’t you think ** _Amaimon?_ **”

The way Rin said his name sent shivers down his spine but he knew he had to do something before Rin got out of control again. Even though part of him just wanted to _ play _ with him again when it inevitably happened. But it was impossible to tell with Rin acting so erratic so Amaimon went to do damage control. Indifference still shining through, he looked up into warped blue filled with dancing flame and slitted red and Amaimon slowly reached up to cup Rin’s cheek in a rare act of human affection.

“They don’t deserve to be burned by your beautiful blue flames Rin. Why don’t I go get us both something to eat and you can get another half hour of sleep hm? You were up all night tossing and turning.” He expertly kept the instinctual fear reaction at bay as he spoke and brushed a clawed thumb against Rin’s lips. His attempts could invite ire or acceptance, and the not knowing made adrenaline spike in his veins.

Everything was quiet for a moment before Rin grabbed Amaimon’s hand and brushed his fangs against his flesh. His eyes flashed dangerously and a low growl rumbled in his chest as he smirked; his voice was dark and alluring when he spoke.

“Why wait when I can just eat right now? After all, you _ did _ wake me and I’m so very ** _hungry.” _ ** Danger laced Rin’s words and Amaimon shivered. ** _ “Won’t you give me a little bite, Am~ai~mon~?_ **”

Pupils dilated and slivered into slits, tracking every moment as a tapered tongue slid down his wrist and traced over his pulse. A low, hungry growl rumbled in his chest as he unknowingly canted his hips against Rin’s making the younger demon ‘tsk’ as he reached around and pushed his hips down with surprising force.

“**So needy Amaimon. If you’re still, I might ** ** _reward_ ** ** you after I finish.**”

He could do nothing except swallow audibly while watching Rin give a gentle kiss to his pulse before breaking the skin with elongated fangs. Rin groaned as warm blood traveled down his throat and tension seemed to drain from his body. He began grinding his hips and pushing his thighs against Amaimon’s, oblivious to the effect his actions had and only chasing his own pleasure. 

Blood trickled down his chin and Amaimon moved to lick it up before capturing Rin’s lips in a bruising kiss. Another thought had him biting down on Rin’s lip and greedily swallowing that sweet liquid carrying his essence, the heady flavor of Gehenna. He could feel his hardening cock throbbing in his suddenly too tight pants and let out a pained moan.

Minutes passed with the only sounds being Rin tearing open Amaimon’s vessel to get at his blood every time he healed and Amaimon thrusting up against him, desperate for Rin to move to the next step, for his reward.

Those captivating eyes opened and Amaimon was about to start begging when Rin froze, mouth slack around his wrist. In the next moment he let out an indignant squeak and was across the room faster than Amaimon could even blink through the lust filled haze swirling in his vision.

“Wha-what are you doing here Amaimon?” Panic surged in Rin while Amaimon tried to understand where the warmth in his lap had gone and why it was suddenly so loud. When he didn’t answer in time, Rin turned his focus to the remnants of the other day, a frustrated yowl breaking past his lips at the sight of the two gaping holes in the wall of his bedroom and bathroom. “And why are there _ holes _ in the walls? Dammit,Yukio is gonna kill me when he comes home!” 

Looking at the clock, Rin cursed, fist meeting the wall by the door he darted through, just barely remembering to pull on his uniform and grumbling echoing back to Amaimon from down the hall. “Fuck! I’m gonna be late to cram class, _ again _.”

What?

Cracks spiderwebbed in the fragile siding of the wall where Rin had unknowingly struck too hard, leaving more damage he would shout about when he saw it, if the trend continued.

If Amaimon were in his right mind, he would’ve been worried over the lack of Rin’s usual way of talking about that twin of his. How he didn’t automatically start grumbling about how he hadn’t dreamt of _ him _ in the past two days and with the week coming to a close, it was even more worrying than usual. 

But Amaimon was still reeling over the sudden change and he groaned in frustration, smacking his head back against the tile floor when he realized he had to deal with his _ problem _ alone.

It looked like he wouldn’t be getting his reward after-all.

  
  


§

  
  


Rin scrambled in through the door of the classroom seconds before the teacher walked in. Ignoring the glare from Neuhaus and the slightly worried stares of his classmates, he hurriedly sat in his seat and pulled out a notebook, tapping a pencil to it in restless patterns. 

Shiemi opened her mouth to say something but closed her mouth with an audible snap of her jaw when her gaze flicked to something on his face that seemed to startle her. Rin wondered if he’d gotten food stuck in his teeth but realized that couldn’t be the case because he hadn’t eaten anything that morning. Still, feeling a sudden bout of self-consciousness, he wiped at his face and hoped he got whatever it was away. Shiemi would tell him if she saw anything, he was sure. 

A scent caught his attention and Rin focused until he narrowed it down to the sleeve of his uniform he’d wiped his mouth with, brows furrowing as he sniffed, further still when the identity of the scent registered. Blood, not his. But where had it come from? 

Had he been in a fight? No. Unease curled in Rin. He hadn’t been in a fight that he could remember. But trying to get to the source of the foreign blood hidden by his dark uniform just made Rin’s head hurt and irritation grow until he gave it up, not wanting to have another miserable class because he had a headache. 

Though at least he knew why Shiemi had looked so concerned. Rin winced and tried to smile at her. He frowned when she wouldn’t meet his gaze, eyes pinned to her notebook. He’d just explain himself after class.

As the class stretched on, Neuhaus’ glare seemed to burn holes in Rin’s skull even when he closed his eyes and laid his head down on the desk. While it would usually make Rin feel anxious, he was instead getting angrier and angrier by the second.

He knew that the teachers tended to look at him with varying levels of contempt, apathy, or wariness, Neuhaus more so than any other. Whether it be because of who his birth father was, the blue night or just him simply existing, he could imagine the whispers in the halls to each other when he wasn’t around, when Yukio wasn’t there to quell them with his presence. 

Thoughts of Yukio twisted around in Rin’s head, combining with the animosity of the exorcists into a tangled knot. Yukio never really said anything to the other professors, had told Rin from the start they would say those things. And he knew they would! But- hurt stabbed into Rin’s chest, the hand he rubbed there doing nothing to assuage it- Yukio never _ disagreed _ with them either, not even in conversations alone with Rin.

It hurt. Rin couldn’t stop thinking about it now that he’d started. Why didn’t Yukio ever back him up? Even if he couldn’t because of his position as a teacher, why not in private? All the way back at the start when he’d told Rin to expect the hatred and fear, that they would say he’d killed their dad, killed Shiro, Yukio had never quite said what his thoughts were and where he stood.

Did Yukio share their views? Did he think the same as the others? Did he still blame Rin for everything that had happened?

Hurt crashed into rage. Rin became aware in the back of his mind that he’d gripped his claws deep into the desk, that Neuhaus had left and there was new attention was on him now, that everything had gone silent.

Shiemi was finally looking at him, why had he wanted her to look at him? Rin bared his fangs and saw her flinch, the scent of fear rolling off her and burning at his nose.

Someone shifted and Rin whipped his head back to look at them while clenching his jaw to stop the dangerous growl that threatened to come from deep in his throat. 

‘_ Why are they all looking at me like that? Like I’m some rabid fucking animal. They’re afraid. Why?’ _

A voice slithered in his ear, dark and comforting amidst the confusion.

‘** _Of course they fear you Rin, you’re the Prince of Gehenna. The one who inherited the royal blue flames of your Father._ **’

Rin grabbed fistfuls of his hair, claws digging harshly into his scalp. In his peripherals, Bon rose from his seat, making as if to move towards him and sending his hackles raising in warning. Shima reached out, trying to stop Bon but only serving to bring awareness to Rin that he was surrounded, too many bodies between him and the door.

The voice in his head was getting louder and his anger was growing, becoming something unfamiliar to him. Stemming from something far more inhuman. Out of his control.

Izumo furrowed her brows and began fidgeting in her seat, the movement stealing Rin’s focus towards her as her wariness and fear pressed in on his overwhelmed senses.. 

She grabbed Bon’s wrist as he walked by in a vice-like grip and started furiously shaking her head when he looked at her while Rin glared.

“Don’t. Please just leave him. He’s not-he’s not himself,” she whispered shakily, her voice leaving in breathless shivers. So, she was the same as the exorcists, her defense of Rin on the train had been empty after-all. Why was he surprised? Why did it hurt so much? _ Why was everyone doing this to him? _

Bon snapped his wrist from her and hissed, though hesitation slipped through the brash exterior he wore.

“What the fuck is your problem?” His harsh question sent Rin’s claws digging deeper, startled and curling tighter in his seat as he waited for the explosion. “He’s our _ friend _ Izumo and I’ll be damned if I leave him alone while he’s suffering like we all did when we found out what he was.”

‘**Yeah, right** ,’ the voice scoffed in his ear, a bitter tar seeping up in his throat to suffocate him. ‘ **The big rooster likes to strut around, feeling full of himself and like he’s some great leader. But get him alone and he’ll change his tune, just like the rest of them.**’

Rin squinted up through his bangs, noticing they’d plastered to his scalp with his sweat, and watched Izumo pull her arm back like she’d been burnt, tears in her eyes but the fight gone out. 

Still, Bon moved closer to Rin, pupils flicking to the claws Rin felt were wet with blood.

An audible swallow came from Bon, his own weak, human fingernails digging into his palms like he tried to calm himself. He couldn’t hide his rabbiting heart. He was visibly scared, the fear reflecting back on Rin and ramping his own emotions further, heightened by the chaotic scents in the confining room.

And he was too close, hand reaching out to touch, going for Rin’s shoulder. Was he going to attack? Would this be the moment they all betrayed him? Revealed their true feelings and fears? 

Before Bon could speak and confirm everything Rin couldn’t take to hear, he found his voice, hearing it rasp shallow and pained through a too tight throat. He shook as more of his blood seeped onto the floor; the familiar metallic scent being the only thing grounding him in that moment as he tried everything to ignore Bon’s hand on his shoulder.

“Don’t- please don't touch me.” But Bon ignored him, squeezing his shoulder tighter before he opened his mouth to speak only to be cut off by a low growl and Rin’s heated glare. Blue light put shadows on Bon’s face that Rin didn’t bother to think about.

He hadn’t let go.

_ Let go let go let go! _

Power welled up around Rin, a thrumming buzz in his ears that told him to strike while his prey was in his grasp. Strike before he was struck. 

Visible trembling shook Bon’s limbs, eyes blown wide in ** _fear_ ** and he started to frantically step away from ** _the demon_ ** in front of him but Rin was faster. His clawed hand lashed out and wrapped around Bon’s wrist, claws digging harshly into flesh.

“I said, **don’t fucking touch me!** ” Eyes filled with swirling blue flames met frantic brown and Rin _ snarled _. Standing up and throwing Bon like he was nothing more than a ragdoll across the classroom where he slammed into Shima and Konekomaru.

Shouts went up around the room as Rin darted his gaze, searching for this next target.

Moments later, as if a switch flipped, Rin let out a choked gasp, bloody hands returning to grabbing fistfuls of his hair and whispered apologies falling from his lips 

“I’m sorry, I’m so, so sorry. Oh god, what did I just do?”

A questioning sound at the door had Rin jerking his head around to see a teacher, horror blooming in their eyes at the sight that greeted them and demands for an explanation already forming. No one could seem to answer them but the pained moans from Bon were more than enough, the teacher rounded on Rin with righteous fury only to almost be knocked down as he ran out of the classroom before any of them could register what happened.

  
  


§

  
  


His mind was a swirling vortex of questions as he ran towards his dorm, not even realizing or caring about how fast he was going. He just had to get away, away from the voice in his head, the fearful stares from his friends. 

What scared him the most wasn’t the fear and hate in everyone’s eyes, but the all-consuming rage he felt from seemingly out of nowhere.

‘Why? Why did I do that to Bon? He was just trying to help me with…something. But can’t remember what.’ 

He slowed to a walk as he tried to wrap his head about whatever was going on.

‘They all looked at me with such _ fear _ . ** _Delicious fear_ ** ….wait _ nononono!’ _

_ What was happening to him? _

Rin’s bangs fell over his face as he shook his head. Trying but failing to get rid of the confusion and the bubbling rage that he still felt slithering under his skin like a snake ready to strike.

** _‘Let them fear you Rin. Let them fear _ ** **us** ** _. You can’t deny how good their fear felt, especially when you threw that worthless human away like a paper doll. There’s no use lying…least of all to yourself.’_ ** There was that strange voice again. He could feel whatever it was scraping at the walls of his mind like a goddamn mental patient trying to free himself from solitary.

**‘They can lie to you all they want, just as long as you don’t lie to yourself.’**

Yes, that was true, but- Rin shook his head more furiously, unable to deny how _ good _ it felt. To make Bon, the same jerk who picked on him when he first arrived at True Cross like a buffed up version of Reiji, fear him and to physically _ hurt _ him. 

The darkness bubbled up in him, escaping as a harsh laugh from his lips when he thought back to the way Bon flew through the air like a rag doll. 

It was fine, he was just making sure Bon knew to keep his hands and comments to himself next time. He wouldn’t touch him again.

Rin was in front of the door to his dorm before he knew it and mentally prepared himself to be greeted with the same empty space he’d grown used to this past week, wondering if Amaimon would still be there and if he even wanted him to be. 

He ran a hand through his hair and sighed as he opened the door but instantly perked up at the sight that greeted his eyes.

“Yukio you’re back! I thought you were gonna be gone for at least another week?” Rin cocked his head in confusion and Yukio turned around.

Then the scent registered.

What Rin saw held in Yukio’s arms made his blood freeze and he didn’t even notice the glare pointed at him as he looked into dull green cat eyes. 

Kuro was curled up against Yukio’s chest and Rin gasped when he noticed the still bleeding cuts littering the cait sidhe’s small body. The smell of blood permeated the air along with the anger he could see building in Yukio.

“Kuro? Wh-why are you bleeding so much? Where did those injuries come from?” He felt tears prick at the corner of his eyes, a hot mix of confusion and fear burning in his gut adding to the turmoil that had plagued him for weeks now. His voice came out in a bare whisper as he spoke to his familiar, but Kuro refused to say anything, opting to bury his head into the crook of Yukio’s arm.

The rest of the scene registered to Rin. Yukio’s medical kit, already opened to reveal the contents he’d been in the process of using on Kuro before Rin had interrupted. A scent that itched at his nose took him a moment to place, but then he saw the cuts on Kuro release steam and rot even as it tried to heal. He’d felt that before. Holy water. And Kuro wasn’t a high enough level to fight off the effects.

“I should be asking _ you _ the same thing,” Yukio said in a hiss, anger staining his words and tearing Rin’s focus from Kuro to see a glare from furious blue eyes.

“What did you do Rin?” He didn’t know, he didn’t know! “I was on an important mission and Kuro ran all the way to find me- he almost got killed!”

Rin could only stare in shock. He tried to understand what Yukio said but every word had started turning into white noise, static in his ears, as he watched the shivers go through Kuro’s body.

‘_ Is he blaming _ me _ for this?’ _ Did Kuro blame him for this? 

He opened his mouth in a futile attempt to deny the accusations, to explain that he had no idea where Kuro was all this time. 

But Yukio spoke again, cutting him off with a growl as he set Kuro on the table to start reversing the damage from the holy water with harsh, practiced movements, “I thought you were under control again. I thought I could trust you by yourself!”.

“Yukio I-“ he could trust him, why _ couldn’t _ he trust him? 

“You what, Rin? You can explain?” Yukio snapped back, finished with Kuro and clenching his fists, facing Rin fully in confrontation. “There’s holes in the walls, Ukobach is missing, Kuro ran hundreds of miles to nearly get killed by other exorcists just to drag me back here early from my mission.” 

“And you’ve got blood on your face!” Yukio’s shout sent Rin reeling back, hand going to his mouth and feeling the flecks of dried blood come away to freckle his fingers when he pulled away to look. 

“When are you going to stop being such a loose cannon?”

  
  


The words pounded in Rin’s head, following the rushing pulse and acid fury filling him from the inside. He wasn’t a demon. It wasn’t his fault! Why was Yukio looking at him like that? Like he was dangerous, like he was a monster. Like he was a demon.

And Yukio was every bully who’d shouted those words at him, every attack thrown his way, every hit that struck.

“What would dad say if he could see you now?” Rin’s world washed in shades of red, then blue, scenes like an afterimage overlaid on Yukio’s snarling face, of Shiro, yelling at him, telling him he had to leave, that he was a demon.

“You’re acting like a demon!”

Fire roared to life around Rin, Yukio’s responding shout lost to the flames washing the room in monochrome blue. What wasn’t lost was the gun Yukio pulled on automatic, trained directly on Rin as Kuro yelped and fled the room. 

“What did I say about pulling your gun on your own brother, _ Yukio? _” Rin let the words hiss out over the flames, seeing himself reflected in wide blue eyes behind the frames on Yukio’s face.

_ How dare he, how dare he! _

“Rin, stop!” 

But he hadn’t listened to Rin. Yukio never listened to Rin.

_ Why won’t he believe me? _

Yukio didn’t lower his gun, Rin felt his resolve waiver.

The door to the dorm slammed open just as the last of Rin’s resolve ripped apart. 

Mephisto appeared through the door followed by an entourage of exorcists and the exwires. Shima and Konekomaru were missing. Bon was missing. Rin couldn’t remember why that was important.

In the back of Rin’s mind, a voice laughed and laughed until it was the only thing he could hear.

**Finally.**

  
  


§

  
  


“This has spun wildly out of control. Mr. Okumura, you’re not supposed to be home from your mission yet.” Mephisto’s voice held hard malice as he spoke. Even the other exorcists that flanked him took an instinctive step back at the dark aura he exuded.

Yukio tried to speak but was startled into silence by a loud pained shriek that shook the walls coming from Rin, who’d fallen in a pool of his own blood. 

Stunned gazes met the sight, thoughts of a second Blue Night welled with the growing fires surrounding Rin. Mephisto sensed the power rising to critical levels and snapped to move the more vulnerable humans behind him, though he didn’t think that would do much if he couldn’t do damage control.

A pained gasp escaped from Yukio, a smaller ball of blue fire melting his gun to scalding ruin that burned his gloves and blistered his fingers as he shook the weapon free.

But Mephisto didn’t pay him any attention, bringing the group back out further from the epicenter of destruction. Still, he could see into the open doorway and his hearing picked up exactly what transformation Rin went through.

Slighter power stole his focus and he shot a quelling glare Amaimon’s way as he arrived to witness Rin’s rebirth. It did little to diminish the obvious interest in gold eyes, Amaimon’s fascination with Rin suddenly making several things apparent to Mephisto. He knew then how Rin had reached this stage and hoped Amaimon knew what punishment awaited him after he dealt with the current problem.

The wretched screams died down and Mephisto could see Rin’s curled up form amongst the flames. A moment passed and a sickening crunch reached his ears, sending his pupils slivering at the violence of it.

He could only guess from the sound that Rin’s bones were lengthening and rearranging themselves and he could only imagine the immense pain that his younger brother had to be in. He’d broken the seal. 

The sound of flesh ripping and the scent of blood soon followed, which only served to worry him more and he darted a glance towards his precious pawns to see how they would handle the sight. The careful scan revealed Kamiki Izumo watching the flames with strange intensity. 

The daughter of the Inari shrine maiden would be able to guess what was happening to Rin by what she felt in her blood. Memories of her mother going through a similar but oh so painful demonic transformation certainly added to that glaze of fear in her eyes.

A different sort of panic than what each of the others present in the vicinity felt, he imagined. 

Mephisto prepared himself to deal with a volatile Satan spawn and watched Rin rise in his flames, reborn.

  
  


§

  
  


Everyone could only look on in horror, weapons held in trembling hands, not one of them having experienced _ anything _ like this before. After what seemed like an eternity, things became eerily silent and still as the wall of blue flames sizzled out with a hiss. 

Shocked and fearful gasps echoed throughout the room at what creature now stood where Rin was just moments before. 

A being, tall and lithe, stared down at the exorcists through familiar warped blue eyes, red irises slit and narrowed on the two demon kings before moving on over to the exwires. Long, ram-like black horns protruded from Rin’s forehead underneath white hair, and his exposed torso seemed to cave in on itself but was still lined with lean muscle. 

The end of his white furred tail was wreathed in royal blue flames and his claws and fangs seemed longer than he’d ever had them, their sharpness able to _ easily _ rip through flesh. A long, tapered tongue ran over his fangs and he flapped his massive, bat-like wings before folding them against his back.

His voice was anything but human as he spoke and it sent chills down the spines of everyone present.

**“You like what you see~?”** He stretched before walking towards the exwires and exorcists and all of them took an instinctive step back out of his way. Even Yukio frantically scrambled away from this _ demon _ wearing Rin’s face.

Rin stalked up to Mephisto who hadn’t moved an inch and smiled a dark Cheshire grin filled with too-sharp teeth, the points of his fangs peeking out from his lips. His words were too quiet for any of the humans to hear but to a demon’s senses, it came loud and clear.

**“Long time no see~” ** Rin cooed. **“What’s it been, a week?”**

Precisely a week, Mephisto knew, since their confrontation and the initiation of their wager.

**“Aww what’s wrong? Are you upset that you lost our little bet, Samael?”** He tilted his head like a predator eying down prey, taking Mephisto’s silence along with the slight twitch of his eye as answer enough. 

Dark chuckles began, then turned into howls of laughter that reverberated through the abandoned dorm. Rin’s inhuman voice echoed through the room, making his next words audible to everyone.

**“Betcha didn’t see this happening in any of your timelines, huh?”** He motioned towards the downed and visibly shaking form of Yukio without his gaze leaving Mephisto’s. **“You have this little human brat to thank. His harsh words and calling his own brother a ** ** _demon_ ** ** broke poor Rin’s already fraying resolve. The gun being pointed to his head was the cherry on top but it made my inevitable ** ** _release_ ** ** that much sweeter.”**

The grin Rin wore grew impossibly wide as he turned towards Yukio, enjoying the obvious terror his attention inspired. **“I guess I should thank you. After all, dredging old and painful memories was a one way ticket to getting him to give up.”**

  
  


**“The thing is though,” ** Rin said with a careless hum, tapping a claw to his chin as if in thought, ** “none of you knew how much he was trying, fighting, to hold me back because he cares so much for his pathetic human ** ** _friends_ ** ** and ** ** _the last remaining member of his family_ ** ** and even though he was so close to giving up, he never did.” **

Flinching met Rin’s words, Shiemi crying soundlessly as Izumo trembled in place. But Rin was correct, his mental fortitude would have been severely compromised by the lack of support. Irritation bit at Mephisto, knowing Rin would have withstood it fine if he hadn’t fallen past the tipping point with Yukio’s early return. 

**“Why, you might be asking yourselves?” ** The cruel smile drifted across bared fangs while Rin scanned his audience, " **Because he didn’t want to become the ** ** _demon_ ** ** that everyone feared him to be. Oh, and Yukio, so sorry about your gun but I’d rather not have a bullet in my head. You understand don’t you? After all, I am your ** ** _brother_ ** **.”**

Yukio grit his teeth, a wounded sound strangled behind them, though Mephisto detected the mixture of frustration and shame that bowed his head.

But Rin’s taunting had been solely aimed at his friends, and he’d forgotten to account for the humans who didn’t care so much about his plight. Through the silence, the cocking of a gun echoed and Mephisto tilted his head to see one of his less precious pawns raise a weapon on Rin. Well, in the same way he’d cleaned house during the first Blue Night, he could do with a little culling of the herd here.

Rin scoffed and waved a clawed hand, making the weapon burn from an invisible heat before blue flames roared to life around the unsuspecting exorcist. His blood curdling screams were heard momentarily as he was engulfed in flame and reduced to ash in seconds. 

Fear drove weapons from the remaining few who held them, falling with a clatter to the ground while Rin giggled at the reaction he’d caused.

“W-why? You killed him. Why?” Rin’s laughter stopped at the hoarse whisper from Izumo where she stared up from her kneeled position, body limp in horror.

A beat and Rin vanished from in front of Mephisto to mirror her, a gentle finger raising her chin so he could meet her gaze.

**“Shh shh, Izumo,” ** Rin said, hushing her despite the panic his actions elicited in the ones forced to watch. **“It’s ok. Rin would ** ** _never_ ** ** harm a defenseless human, but I’m the farthest thing from the Rin you knew.”**

Izumo hiccupped, pinned beneath the weight of Rin’s gaze and words.** “I’m his true self and hey, if he didn’t point his weapon at me, I wouldn’t have killed him. But, you have my word that I won’t harm another human here. Ok?”**

Strangely enough, Rin’s voice was soft, hypnotic, as he spoke his promise. Mephisto cocked his head at the display, though he prepared to remove his key players if Rin decided to change his mind and he let his power lie in wait to use.

“Rin,” Izumo said in a gasp, expression saying she desperately wanted to believe him, though the claw so near her vital throat brought cold sweat to her skin despite the heat of Rin’s flames, “please don’t-”

She wasn’t able to complete whatever her request would have been, Rin rising to his feet, ignoring the pleading cry from Shiemi and the hand she brought up to his retreating form. Wise, on his part, Mephisto noted, knowing she above all held the highest potential of waking the other part of Rin crushed beneath this one.

But he had to contend with that demon now, allowing a cheerful smile to settle on his lips as Rin stalked towards him again.

“Then, now that you’ve won our wager, what will you do, Rin?” He was curious. Rin wasn’t much of a planner in any timeline, nevermind one his other half had been allowed to reign.

Gleeful blue eyes swept over him before Rin answered,** “worried I’ll harm one of your precious exorcists, ** ** _Samael?_ ** ** Don’t be, they're worth about as much as the cinders they’d make but I don’t really care about them.” **

Well, that saved him the effort, Mephisto tilted his head in acknowledgement, waiting for the addendum he knew would come. 

**“But,” ** Rin continued, ** “if one of these pathetic humans comes after me the bet is off. ** ** _Am I clear?_ ** **”**

Crystal. Mephisto hid a wince as the pressure of Rin’s power swelled, invisible to human eyes but with gravity that suffocated him beneath its aura.

He distantly heard Amaimon whimpering behind him. The weaker kings were always more sensitive to Father’s presence, and, as it seemed, Rin’s now as well.

Both demons stared each other down for a few tense moments before Mephisto spoke.

“I can assure you that none of Japan Branch’s exorcists will come after you. The other branches, though, I have no jurisdiction over, you understand.”

The warning brought a smile to Rin’s face and Mephisto blinked when he lifted a hand to rest on his shoulder in a companionable hold. Whether that hold was a mimicry or this version of Rin carried some level of affection for him was unclear at this junction. He would have to act as if it were.

“Be wary of the Grigori, younger brother,” Mephisto said, watching to see what his caution would bring out in Rin, "not even I can go against them and you are too new, having only just awakened. When they hear about this, they’ll come after you with everything they’ve got. And even ants can rip a larger predator whole if it’s not careful.”

Rin’s demeanor changed and his eyes darkened momentarily in thought before the expression smoothed back to a carefree smile. Mephisto knew he’d gotten his point across, now it was up to Rin to determine what he would do.**“I will. Thanks for the tip, Samael,” ** Rin said, finally, **“I think I know where I’ll be headed, now. You’ll know where to find me.” **

His hand left Mephisto’s shoulder after giving it a last squeeze and looked at Amaimon, brushing past Mephisto to step closer to him with a wide grin. 

**“Hey, you must be bored of this place,” ** Rin ran his gaze down Amaimon, who perked up at the attention and possibility it suggested, **“unless you’d rather stay here and explain the past week to Samael.”**

Yes, he could see Amaimon knew exactly what waited for him if he didn’t take Rin up on his offer. Mephisto let his grin sharpen and enjoyed the slivering of Amaimon’s pupils. Besides, he could always remind him of his failure at his specific task at a later time. He was patient.

Rin jerked a thumb over his shoulder to the door before stuffing his hands in his pockets and walking towards it, not even bothering to check if the earth king was following. 

With a long look at Mephisto, Amaimon left, ignoring the stricken humans at his passing.

Then only his pawns remained. Mephisto sighed, taking in the sight of several traumatized humans and knew he’d have a long stretch ahead of him to rearrange plans and pawns to deal with the new board he played on this timeline.

Ushering his precious pawns to leave to recover, Mephisto laid out their orders to meet after they’d rested from their ordeal. Though he could see from the various looks of shock, horror, and grief that they wouldn’t be resting any time soon. 

And poor Yukio, alone in his empty dorm with only an injured familiar as his companion. Mephisto hid a smile, wondering how long it would take him to defect to the Illuminati this timeline. 

He breathed a long exhale from where he watched the sky from the entrance to his academy some time later, wry curl to his lips as he spoke to himself.

“You were always more than a pawn in my game, little brother. I’m sure you’ll put on a good show for me in this new game of ours.”

With a twirl of his umbrella, he disappeared and reappeared back into his office, looking towards the boundary of True Cross with a sly grin.

“Let the show begin~.”

**Notes for the Chapter:**

> hey y’all I did some thinking and this is unfortunately the end >< now before you come after me with torches and pitchforks there WILL be a part 2
> 
> I just gotta do some outlining n stuff before that so hopefully I’ll see y’all again soon and look forward to it ;)

**Author's Note:**

> so um I started a discord server >< come scream at me n stuff https://discord.gg/NqTPyF8


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